Bangladesh Journal of Pharmacology Mini-Review Experimental models for vascular endothelial dysfunction BJP Hexosamine pathway NADPH + AGEs Altered NOS decreased eNOS Vascular endothelial dysfunction Hypo-insulinemia Nf-kb Calpain Up- regulation of cyto- kines PDGF & VEGF Polyol & PKC pathway TREF-6 Adhesion molecules ICAM, VCAM Apoptotic & necrotic factors Glutamate PAII Proinflam- matory mediators DIABETES Introduction The vascular endothelium is the innermost lining of the blood vessel. It is a metabolically active layer that tends to release various substances that control vascular relaxation and contraction as well as enzymes that control blood clotting, immune function, and platelet adhesion (Sandoo et al., 2010). It plays a crucial role in maintaining vascular tone, integrity, and free flow of the blood under normal physiology. Destruction or injury in the endothelial layer of arteries leads to create an imbalance between vasoconstriction and vasodilata- tion factors which complicate vascular endothelial dys- function and lead to cause various other severe cardio- vascular disorders. An increase in free radicle produc- tion (ROS/RNS), NADPH oxidase, xanthin-oxidase or decrease in glutathione, no generation is the underlying pathways involved in the pathogenesis of vascular endothelial dysfunction. Regulation of inflammatory mediators such as intracellular adhesion molecule-1, von Willi brand factor, Nf-kb and growth factors like endothelin-1, VEGF, PDGF, OLGF, and ILs mutually affect vascular endothelium (Balakumar et al., 2008a). Atherosclerosis, hypertension, hyperglycemia, and smoking are considered to be the self-governing risk factors and foremost determinants in the progression of vascular endothelial dysfunction (Hadi et al., 2005). To identify the potential pharmacological targets for vas- cular endothelial dysfunction in different experimental models are designed and employed to induce the vascular endothelial dysfunction. Therefore, this paper aims to review various experimental animal models developed to produce vascular endothelial dysfunction. Animal models Human vascular endothelial dysfunction shares many features which are common with animals. In contrast to direct study on human, animal models are easily manageable, as experimental conditions can be control- led. Vascular and cardiac tissue samples can be taken for detailed biomolecular and histopathological exami- nations. Mice and rats have long served as the preferred A Journal of the Bangladesh Pharmacological Society (BDPS) Bangladesh J Pharmacol 2021; 16: 65-83 Journal homepage: www.banglajol.info; www.bdpsjournal.org Abstracted/indexed in Academic Search Complete, Asia Journals Online, Bangladesh Journals Online, Biological Abstracts, BIOSIS Previews, CAB Abstracts, Current Abstracts, Directory of Open Access Journals, EMBASE/Excerpta Medica, Global Health, Google Scholar, HINARI (WHO), International Pharmaceutical Abstracts, Open J-gate, Science Citation Index Expanded, SCOPUS and Social Sciences Citation Index; ISSN: 1991-0088 Abstract Vascular endothelial dysfunction is characterized by apoptosis of endothelial cells, an imbalance between vasoconstrictory and vasodilatory substances, the imbalance between ROS and antioxidants, vascular remodeling, loss of vas- cular integrity which leads to an increased risk of cardiovascular complica- tions. To date, no therapeutic intervention is available as a promising agent. This may be due to a poor understanding of the underlying mechanism involved in vascular endothelial dysfunction in the pathogenesis. Animal models sharing identical features as that of humans are paramount to understand fundamental physiology, mechanism and to explore new targets for developing therapeutic agents. Thus, it becomes mandatory to re-explore the available animal models for a better understanding of molecular path- ways involving vascular endothelial dysfunction. The purpose of this paper is to review different models for vascular endothelial dysfunction to the outlook for developing new drugs to treat vascular endothelial dysfunction. Article Info Received: 14 April 2021 Accepted: 16 June 2021 Available Online: 1 July 2021 DOI: 10.3329/bjp.v16i3.52948 Cite this article: Garg A, Gupta V, Tomar R, Arora MK. Experimental models for vascu- lar endothelial dysfunction. Bangla- desh J Pharmacol. 2021; 16: 65-83. Experimental models for vascular endothelial dysfunction Anchal Garg1, Vardan Gupta1, Ritu Tomar2 and Mandeep Kumar Arora2 1Department of Pharmacology, KIET School of Pharmacy, KIET group of Institutions, Ghaziabad 201001, India; 2School of Pharmaceutical and Population Health Informatics, DIT University, Dehradun 248009, Uttarakhand, India. This work is licensed under a Creative Commons Attribution 4.0 International License. You are free to copy, distribute and per- form the work. You must attribute the work in the manner specified by the author or licensor M in i- re v ie w species for biomedical research due to their anatomical, physiological, and genetic similarity to humans; sponta- neous, drug-induced, metabolic alteration related and numerous genetically modified animal model have been developed for improving the understanding of the pathogenesis, prevention, and treatment of vascular abrasion and its comorbidities depend on their validity for representing human forms of vascular endothelial dysfunction. As an alternative, endothelial cells culture has been extensively described in the literature for in vitro assessment of oxidative stress, inflammation and proliferation (Le Brocq et al., 2008). The cell culture technique provides a path to explore wide variety of intracellular signalling pathways, with different pur- poses. However, these processes have restrictions rela- ted to phenotypic changes of the cells (Fadini and Avogaro, 2010). Hence, rodent models are preferred models that exhibit progressive vascular endothelial dysfunction is selected for identifying mechanisms involved in vascular endothelial dysfunction and to develop suitable therapeutic substances for its preven- tion. Diabetes-induced Diabetes mellitus is a pathological group of metabolic disorders characterized by chronic hyperglycemia which is mainly due to impairment of either insulin secretion and insulin action or both causing micro- and macro-vascular complications (Baig et al., 2019). Vascu- lar injury due to uncontrolled hyperglycemia is a key reason behind diabetes associated with cardio- and cerebro-vascular disorders. Diabetes-associated vascu- lar endothelial dysfunction involves multiple signaling pathways including elevation of polyol, protein kinase C, hexosamine, pentose phosphate shunt which are overactive and are involved in diabetes-induced vascu- lar endothelial dysfunction. Diabetes-induced oxidative stress also plays a crucial role in vascular endothelial dysfunction. Though multiple compounds at different doses have been identified, which are correlated with the clinical manifestation of diabetes mellitus-induced vascular endothelial dysfunction and are widely used to identify the potential pharmacological targets for vascular endothelial dysfunction. A) Streptozotocin-induced Streptozotocin, a naturally occurring agent obtained from Streptomyces acromogenes used to treat cancer of pancreatic islets of Langerhans but is highly toxic to the insulin-producing β-cells of the pancreas resulting in insulin depletion (Balakumar et al., 2008b). Streptozo- tocin at different doses of 40, 50, 55, 60, or 65 mg/kg intravenous or intraperitoneal route is widely used as an experimental model for inducing vascular endothe- lial dysfunction (Pieper et al., 1997; Zhu et al., 2011; Yin et al., 2014; Brahmanaidu et al., 2017; Kshirsagar et al., 2017; Azemi et al., 2020; Said, 2020). Within 72 hours of administration, a single dose of streptozotocin produces hyperglycemic effects but vascular endothelial dysfunc- tion can be observed after 4-8 weeks. GLUT-2 present on the pancreatic cell uptakes streptozotocin which results in the alkylation of DNA and triggers activation of PARP, polyol, protein kinase C, hexosamine, pentose phosphate shunt pathways, and overexpression of NOX2, leading to ROS/RNS generation and accumula- tion in the endothelial lining of blood vessel aggrava- ting vascular endothelial dys-function. The induced vascular endothelial dysfunction is assessed for decrea- sed aortic serum nitrate levels, T-BARS, GSH, NBT levels as well as increased phenylepinephrine-induced pre-contraction (Balakumar et al., 2009; Nie et al., 2019). Vascular endothelial dysfunction induced by intrave- nous administration of streptozotocin down-regulates the level of eNOS by producing superoxides and per- oxynitrites and also alters GCH-1, responsible for BH4 synthesis which leads to the uncoupling of eNOS from its co-factor BH4 and alters NO bioavailability (Oelze et al., 2011). Streptozotocin in rats (30 mg/kg along with high fat and high sucrose diet), is associated with increased serum von Willibrand factor and decreased acetyl- choline-induced relaxation, the content of aortic angio- tensin converting enzymes, NOs, and expression of eNOS is decreased which are found responsible for reducing the elasticity of the vessels (Yang et al., 2011). Streptozotocin-induced hyperglycemia (65 mg/kg intraperitoneal) is evaluated in vivo and in vitro for expression of calpain-1 protein by Western blot. Un- controlled hyperglycemia persuades hypersecretion of proteolytic enzymes calpain and its isoforms which in turn activates apoptotic and necrotic factors and also alters NOS (Nie et al., 2019). Under streptozotocin- induced hyperglycemia, HAEC (human aortic endothe- lial cell) is found with the expression of TRAF-6 (Tumor necrosis factor associated factor) and related adhesion factors like ICAM and VCAM. This TRAF-6 protein induces vascular endothelial dysfunction by expressing NFKB and AP-1-dependent signaling pathways (Liu et al., 2018). Transcripting factor AP-1 (activator protein) expression increases under the influence of various stimuli like stress, cytokines, growth factors which are associated with MAPK pathway activation. Streptozo- tocin is also responsible for decreasing the expression of sirtuin (SIRT-1) which is responsible for maintaining lipid and whole-body cholesterol homeostasis, decreas- ed levels of SIRT-1 are associated with worsening of vascular endothelial dysfunction (Wu et al., 2018; Pal, 2019). Single intraperitoneal administration of strepto- zotocin not only tends to induce diabetes but also worsens vascular endothelial dysfunction (Ji et al., 2021). C75BL/6 transgenic mice at a single dose of 50 mg/kg intraperitoneal for 5 consecutive days is not only found with elevated oxidative stress, inflamma- tion, and aortic contractility but is also found to decrea- se SIRT-1 protein (Wu et al., 2018), In addition, BALB/c 66 Bangladesh J Pharmacol 2021; 16: 65-83 transgenic mice with intraperitoneal administration of streptozotocin is reported to up-regulate COX expre- ssion which results in increased release of proinfla- mmatory mediators (Nacci et al., 2009). While in alloxan-induced diabetes, oxidative stress is found to be associated with diabetes-induced complica- tions but not associated with vascular endothelial dysfunction whereas in confirmed diabetic rats’ level of eNOS and nNOS is altered and penile erection is reduced when compared to normal rats (Capellini et al., 2010). Despite biochemical alterations, histopathological changes including vacuolization in the endothelium, edema in the tunica adventia, and focal infiltration of tunica media are associated with streptozotocin admi- nistration to rats (Adel et al., 2014). Mechanism under- lying streptozotocin-induced vascular endothelial dys- function is depicted in Figure 1 and different doses and animal models for streptozotocin-induced vascular endothelial dysfunction are summarized in Table I. B) High fructose diet-induced Fructose, a simple ketonic dietary monosaccharide widely used to induce vascular endothelial dysfunction that correlates with clinical features for metabolic abnormalities as it does not only result in hypergly- cemia but also alters the lipid profile by enhancing the levels of VLDL. In addition, the uric acid level in the blood is also affected. Thus, play a crucial role in cardiovascular disorders. A decrease in angiogenesis is one of the significant cell losses governed by a high fructose diet (Khitan and Kim, 2013). Fructose at different concentrations of 10, 20, 60, and 65% w/w, has been noted to induce diabetes and associated complica- tions within 8-12 weeks. A high fructose diet to Sprague -Dawley rat is found to have increased plasma trigly- cerides, cholesterol, fat weight, blood pressure, and decreased glucose tolerance (Babacanoglu et al., 2013; Malakul et al., 2018). In addition, administration of fructose is associated with the increased level of endo- thelin-1, inflammatory mediators, adhesion molecules in the aorta. Phenylepinephrine and potassium chloride contractility are also exaggerated in rats (El-Bassossy et al., 2014). Furthermore, fructose causes an imbalance between superoxides, peroxynitrites, and antioxidants Figure 1. Mechanism underlying streptozotocin-induced vascular endothelial dysfunction. PKc- protein kinase C signalling pathway; PDGF- platelet derived growth factor; VEGF- vascular endothelial growth factor; NfκB- nuclear factor kappa light chain enhancer of activated B cells; ICAM- intercellular adhesion molecules; VCAM- vascular cell adhesion molecule; TRAF-6- tumor necrosis factor (TNF) receptor associated factor-6; NADPH- nicotinamide adenine dinucleotide phosphate; AGE- advanced glycation end products; NOS- nitric oxide synthetase; NO-nitric oxide Hexosamine pathway Streptozotocin NADPH + AGEs DIABETES Altered NOS decreased eNOS Vascular endothelial dysfunction Anti-cancer drug Used to treat pancreatic islets of Langerhans cancer Also destructs beta-islet cells of pancreas Hypo-insulinemia Nf-kb Calpain Up- regulation of cyto- kines PDGF & VEGF Polyol & PKC pathway TREF-6 Adhesion molecules ICAM, VCAM Apoptotic & necrotic factors Glutamate PAII Proinflam- matory mediators Bangladesh J Pharmacol 2021; 16: 65-83 67 Table I Streptozotocin-induced vascular endothelial disorders Species Dose and route Duration Observations Altered biomarkers Reference Male Sprague -Dawley rats 65 mg/kg, intraperitone- ally single dose ↑ blood glucose, total cholesterol, triglyceride and LDL impaired acetylcholine-induced relaxation ↓ aortic and serum NO level Bala- kumar et al., 2008b Male Sprague -Dawley rats 65 mg/kg, intraperitone- ally single dose ↑ levels of calpain-I, ROS/RNS ↓ SOD, GSH-px ↓ aortic and serum NO level, eNOS Nie et al., 2019 Male Wistar rats 60 mg/kg, intraperitone- ally single dose ↑ oxidative stress ↓ vasorelaxation induced by acetylcholine in the aortic rings, NO levels ↑ eNOS uncoupling Zhu et al., 2011 Male Wistar rats 60 mg/kg, intraperitone- ally single dose ↑ oxidative stress, ↑ endothelin-1 ↑ eNOS uncoupling Said et al., 2020 Wistar rats 60 mg/kg, intravenous single dose ↑ NADPH oxidase, Nox-1 and Nox-2 ↑ eNOS uncoupling due to down- regulation of GCH-1 ↑ MDA levels ↑ ROS/RNS Impaired acetylcholine- induced vascular relaxa- tion ↓ antioxidant Oelze et al., 2011 Sprague- Dawley rats 60 mg/kg, intraperitone- ally single admin- istration ↑ NADPH oxidase impaired acetylcholine- induced endothelium-dependent relaxation ↓ eNOS activity ↑ ROS/RNS ↓ SOD Ji et al., 2021 Male Wistar rats 55 mg/kg, intraperitone- ally single dose once a week, for 8 weeks up-regulation of NADPH oxidase, NOX-2 ↑ TGF-β ↑ phenyl-epinephrine induced con- traction ↓ serum and aortic ni- trate/nitrate levels ↓ eNOS Adel et al., 2014 Male Wistar rats 55 mg/kg, intraperitone- ally single dose once a week for 8 weeks ↓ arginino succinate synthase, ar- gininosuccinate lyase ↓ GSH, SOD, GPx, ↓eNOS Brah- manaidu et al., 2017 Male Sprague -Dawley rats 55 mg/kg, intravenous single admin- istration ↑ norepinephrine-induced vaso- constriction ↑ ROS/RNS Impaired endothelial dependent vaso- relaxation ↓ SOD Pieper et al., 1997 Male Wistar rats 45 mg/kg, intraperitone- ally single admin- istration ↑ LDL. TG, TC ↑ Insulin resistance ↑ ROS/RNS/AGE’s leading to un- coupling of eNOS from its cofactors ↓ serum NO level ↓ acetylcholine-induced endothelium-dependent relaxation Kshirsagar et al., 2017 Male Wistar rats 40 mg/kg, intraperitone- ally + high fat diet . 6 weeks fed with high fat diet followed by single administra- tion ↑ overexpression of TNF-α, MCP-1, and NF-κB P65 ↑ LDL, TG, TC ↑ LDL oxidation ↑ ICAM, VCAM, IL’s ↓ eNOS activity and NO bioavailability ↑ ROS/RNS uncoupling of eNOS from its cofactors Yin et al., 2014 Male Sprague -Dawley rats 40 mg/kg, intraperitone- ally + high fructose diet 4 weeks fed with high fat diet followed by single administra- tion ↑ NADPH oxidase ↑ eNOS uncoupling ↑ AGE’s ↑ free radicles ↓ eNOS activity and NO bioavailability Impaired ACh induced endothelium dependent vasorelaxation Azemi et al., 2020 Rats 30 mg/kg, streptozotocin intraperitone- ally + high fat and high glu- cose diet single dose of streptozoto- cin followed by fed for 1 month ↑ blood glucose, total cholesterol, triglyceride, low-density lipoprotein ↑ vWF ↑ phenyl-epinephrine induced con- traction ↑ MDA levels ↓ eNOS activity ↓ NO bioavailability ↑ levels of AGE’s ↑ uncoupling of eNOS Yang et al., 2011 68 Bangladesh J Pharmacol 2021; 16: 65-83 like SOD, GSH tends to create oxidative stress in the endothelial lining of the blood vessel which leads to impaired vasorelaxation (Kho et al., 2014; Shawky et al., 2014). Regarding vascular structural changes, fructose induces thickening of the endothelial wall due to the release and accumulation of various adhesion mole- cules, along with hyperplasia (Zhai et al., 2017) (Table II). Taken together, streptozotocin- and fructose-induced models are widely used for pharmacological evaluation of vasoprotective agents against diabetes-associated vascular endothelial dysfunction. Streptozotocin dose ranges from 50 to 65 mg/kg/day intraperitoneally. Dose selection depends entirely upon the duration of study and frequency of drug administration. Streptozo- tocin 50 mg/kg/day intraperitoneal is required to administer once daily for 5 consecutive days as com- pared to a single administration of 65 mg/kg/day intraperitoneally. In case of fructose is employed ran- ging from 10 to 65% oral solution, again it also depends upon the duration of study as 60 and 65% oral solution of fructose are given for 8 weeks as compared to 10 and 20% oral solution for 12 weeks. However, their effects on biomarkers are the same irrespective of dose. In our opinion, for short-term studies, a high dose is preferred and for chronic studies, small and repetitive doses are preferred. Regarding selection among streptozotocin and fructose, streptozotocin is used for induction of type 1 diabetes, and fructose is preferred for induction of type 2 diabetes. Doxorubicin-induced Doxorubicin (adriamycin) is an anti-cancer drug which belongs to anthracycline class of antibiotic. It is used in treating a wide variety of cancer but due to toxicities like cardiomyopathy and nephropathy, its clinical use is constrained (Carvalho et al., 2009). Excessive generation of mitochondrial ROX impairs endothelial functioning on exposure to doxorubicin. Doxorubicin-treated aortic ring shows abnormal function, induce vascular stress and causes apoptosis of endothelial lining. It also down -regulates the expression of NRF-2 which plays an important role in the protection of vascular endothelial dysfunction (Wang et al., 2015). Doxorubicin 20 mg/kg intraperitoneally on single administration in mouse model decreases the contractile responses to phenyl- ephrine, along with attenuation of relaxant responses to acetylcholine. In addition, decrease in the aortic and serum nitrate, SOD, and GSH levels were observed (Olukman et al., 2009). Administration of doxorubicin (5 mg/kg) for 2-4 weeks is associated with vascular endothelial dysfunction by indirectly altering the level of NO through declining l-arginine (Li et al., 2019). In addition, loss of endothelium function due to marked increase in ROS/RNS is observed in doxorubicin-trea- ted transgenic C57BL/6 mice, as a key role in establish- ing vascular endothelial dysfunction (Clayton et al., 2020). Doxorubicin not only alters the biochemical mediators but also leads to histopathological changes which include thickening of blood vessels, inflamma- tory infiltration, loss of vascular integrity, and vacuo- lization of the endothelial cells when compare to the doxorubicin-untreated aortic block (Li et al., 2019; Table III). To conclude, doxorubicin is used as an experimen- tal tool within the dose ranges from 5 to 20 mg/kg, intraperitoneal, but it’s worth mentioning that 5 or 10 mg/kg intraperitoneal is used for genetically engineer- ed models i.e. C57BL/6 mice model. However, for Wistar rats, 20 mg/kg intraperitoneal of doxorubicin is employed to induce vascular endothelial dysfunction. All these show similarities in altered biomarkers. Nicotine-induced Nicotine exposure through cigarette smoking is one of the major factors playing a crucial role in modulating vascular activity leading to the development of endo- thelium dysfunction which is associated with various life-threatening cardiovascular disorders. Nicotine Table I Streptozotocin-induced vascular endothelial disorders (cont.) Species Dose and route Duration Observations Altered biomarkers Reference C57BL/6 mice 50 mg/kg/ day, intra- peritoneally once every day for 5 consecutive days ↑ aortic contractility, p53 hyper- acetylation ↓ SIRT1 protein ↑ oxidative stress, inflam- mation Wu et al., 2018 C57BL/6 mice 50 mg/kg/ day, intra- peritoneally once every day for 5 consecutive days ↑ COX-2 expression ↑ NFκB p56 ↑ TXA2, PGE2 ↑ oxidative stress ↓NO bioavailability ↓eNOS activity ↓ PPAR-ᵞ and AMPK expression Xu et al., 2019 BALB/c mice 240 mg/kg, intraperito- neally single admin- istration impaired acetylcholine-induced vascular relaxation ↑ expression of TNF-α, NFκB ↑ PGF-1α ↑expression of pro- inflammatory signals ↑ COX-2 expression Nacci et al., 2009 Bangladesh J Pharmacol 2021; 16: 65-83 69 Table II Fructose-induced vascular endothelial disorders Species Dose and route Duration Observations Altered biomarkers Reference Male Sprague- Dawley rats 10% orally ad libitum 12 weeks ↑ blood glucose, total cholester- ol, triglyceride and LDL ↓ acetylcholine-induced vaso- relaxation ↓ aortic and serum NO level, eNOS, p-eNOS ↑ ROS/RNS Malakul et al., 2018 Male Kunming mice 20% orally ad libitum 8 weeks ↑ serum total cholesterol, tri- glyceride, LDL-C, TXA2 and endothelin-1, AST and ALT thickening of the endothelial wall, accumulation of adhesion molecules and hyperplasia ↓ HDL-C, PGI2 serum and aortic eNOS levels ↓ SOD and GSH Zhai et al., 2017 Male rats 65% orally ad libitum 8 weeks ↑ fat weight, blood pressure, plasma triglyceride, total choles- terol levels, and oral glucose tolerance ↓ aortic and serum NO level, eNOS, p-Enos increased ROS/RNS (Kho et al., 2014) Male Wistar rats 10% orally ad libitum 6 weeks ↑ serum levels of glucose, insu- lin, uric acid, TNFα, lipids, AG- Es exaggerated contractility to phenylepinephrine and KCl and impaired relaxation to acetylcholine El-Bassossy et al., 2014 Male Sprague- Dawley rats 60% orally ad libitum 8 weeks ↓ fasting glucose, GSH and MDA levels, serum total choles- terol, LDL-C, C-reactive protein level and LDH ↓ aortic and serum NO level, eNOS, p-Enos ↑ ROS/RNS ↑ phenylepinephrine-induce contraction Shawky et al., 2014 Male rats 10% and 20%, orally ad libitum 12 weeks ↑ plasma triglyceride, VLDL, cholesterol, insulin and glucose levels, but not body weights impaired NO mediated relaxation alters vascular reactivity to insulin, endothelin-1 in conjunction with insulin receptor substrate-1, endo- thelial nitric oxide synthase, inducible NOS mRNA/ proteins levels in aorta Babacanoglu et al., 2013 Table III Doxorubicin-induced vascular endothelial disorders Species Dose and route Duration Altered biomarkers Reference Male C57BL/6 mice model 10 mg/kg, intraperitone- ally 4 weeks impairs endothelial function ↑ mitochondrial reactive oxygen species (ROS) Clayton et al., 2020 Wild type male mice C57BL/6 model 5 mg/kg, intra- peritoneally 2 or 4 weeks ↓ level of arginine-NO metabolite ↑ level of vascular damage ↓ vascular relaxation, vascular NO generation ↑ blood pressure apoptosis, and oxidative stress Li et al., 2019 Wistar rats 20 mg/kg, intraperitone- ally ↓ NO formation, eNOS and iNOS ↓ contractile responses to phenylephrine, but also attenu- ated the relaxant responses to acetylcholine Olukman et al., 2009 Adult male Sprague -Dawley rats 15 mg/kg, intraperitone- ally 14 days ↑ ROS/RNS ↑ MDA ↑ expression of inflammatory mediators (ICAM, VCAM, TGF-β, VEGF) ↑ apoptosis altered vascular integrity and vascular tone Wang et al., 2015 70 Bangladesh J Pharmacol 2021; 16: 65-83 aggravates multiple inflammatory and metabolic proce- sses. The various vascular endothelial dysfunction is oxidative injury, endothelial damage and dysfunction, enhanced thrombosis, chronic inflammation, hemody- namic stress, adverse effects on blood lipids, insulin resistance and diabetes, reduced oxygen delivery by red blood cells, and arrhythmogenesis. The doses of nico- tine are 2 mg/kg (Balakumar et al., 2008c) or 0.6 mg/kg (Si et al., 2017) for 28 days via intraperitoneal route to induce vascular endothelial dysfunction in experimen- tal animal models. The induced vascular endothelial dysfunction is evaluated for various parameters like serum nitrate, aortic nitrate, TBARS, GSH, and SOD levels. Increased expression of TNF-α, interleukin 1β, CD36, NADPH+ are responsible for the production of ROS/RNS which in turn creates a burden on the endothelium of the vessel, which plays a key role in progressing vascular endothelial dysfunction. This oxi- dative stress induced by nicotine alters the vascular integrity, elasticity of blood vessels and increases phenylepinephrine-induced contraction (Chakkarwar, 2011). Chronic exposure to nicotine causes angiogenesis -mediated inflammation, ischemia, atherosclerosis by binding to α7 nAchR’s. In experimental mice model, nicotine is also found responsible for expressing NLRP- 3 inflammasomes which in turn cleaves pro-caspase-1 and pro-inflammatory mediators, generating ROS/RNS via down-regulation of special endothelial receptors ZO -1 and ZO-2 which cause macro- and micro-vascular injuries (Zhang et al., 2019). Nicotine also accounts for the up-regulation of ADMA which is an endogenous eNOS inhibitor contributing to increased vasoconstric- tion (Taneja et al., 2013). Not only endothelial cells but adipocytes have also been reported responsible for vascular injuries as they are found to secrete various inflammatory cytokines (IL-1β, IL-6, TNF-α, NF-ĸb,) Table IV Nicotine-induced vascular endothelial disorders Species Dose and route Duration Pathways Altered biomarkers Reference Male mice 2 g/kg/ day, intra- peritoneally 2 weeks ↑ NLRP-3 inflammasome ↓ ZO-1 and ZO-2 epithelial and endo- thelial receptors ↑ cleavage of pro-caspase-1 ↑ production of IL-1β lysosomal release of cathepsin B Zhang et al., 2019 Male Spra- gue-Dawley rats 0.6 mg/kg, intraperito- neally 28 days ↑ oxidative stress, low NO bioavaila- bility ↑ accumulation of vascular adhesion molecules vascular wall thickening inflammatory response loss of vascular integrity ↑ vascular remodelling and oxi- dative stress ↑ phenylephrine-induced vaso- constriction Si et al., 2017 ApoE-/- mice 0.1 mg/mL, orally ad libitum 12 weeks ↑ ERK1/2 signalling ↑ expression of adhesion molecules ICAM and VCAM promoting adherence of leukocytes ↑ NF-κB-dependent expression larger atherosclerotic plaques loss of vascular integrity ↑ vascular remodelling and oxi- dative stress Qin et al., 2020 Sprague- Dawley rats with diet- induced obesity 100 mg/L, orally ad libitum 20 weeks ↑ TNF α, interleukin 1β, ↑ CD36 ↑ proinflammatory genes ↑ NADPH oxidase ↑ systolic blood pressure, aortic superoxide production ↑ impaired endothelial nitric oxide synthase and ↓ endothelium-dependent relax- ation to acetylcholine Liu et al., 2017 male Wistar rats 2 mg/kg/ day, intraperito- neally 4 weeks ↑ serum cholesterol, triglycerides and high-density lipoprotein. ↓ expression of mRNA for p22phox and endothelial nitric oxide synthase loss integrity of vascular endo- thelium ↑ serum TBARS ↑ aortic superoxide anion con- centration Chak- karwar, 2011 Wistar albi- no rats 2 mg/kg/ day, intraperito- neally 4 weeks ↑ generation of ROS/RNS ↓ acetylcholine-induced endothelium -dependent relaxation ↓ aortic and serum nitrite/nitrate ↑ serum TBARS ↑ generation of ROS impairing endothelial integrity Balakumar et al., 2008c Wistar albi- no rats 2 mg/kg/ day, intraperito- neally 4 weeks ↓ expression of PPARγ ↑ vascular oxidative stress ↑ activation of NADPH oxidase ↑ xanthine oxidase ↑ mononuclear leukocyte adhesion ↑ expression of adhesion molecules such as VCAM-1 and ICAM ↓ expression of eNOS ↑ the generation of ROS impairing endothelial integrity Taneja et al., 2013 Bangladesh J Pharmacol 2021; 16: 65-83 71 and adhesion molecules (ICAMS, VCAMS) selectively in the presence of nicotine. Persistent exposure of nico- tine acts through pre-ganglionic nerve fibers leading to activation of the sympathetic system, increasing epi- nephrine levels which ultimately constricts blood vessel, increase cardiac output and creates a burden on the endothelial layer which results in vascular endothe- lial dysfunction. The endothelial lining of the aortic block of nicotine-treated rats is destructed, and vascular integrity loss is also observed due to the inflammatory infiltration (Si et al., 2017). Concomitant administration of nicotine and a high-fat diet to rats is associated with an increase in diameter and the intense destruction of the endothelial (Liu et al., 2017) suggesting the syner- gistic effect of nicotine and high-fat diet in the induction of vascular complications. Table IV concludes induction of vascular endothelial dysfunction at different doses of nicotine. Considering all the studies, it may be concluded that for pharmacological evaluation of vasoprotective agents, nicotine-induced vascular endothelial dysfunction models are widely explored as it provides the clinical relevancy for lifestyle-related vascular endothelial dys- function. Regarding dose selection of nicotine, it ranges from 0.6 to 2 mg/kg/day that mainly depending upon the frequency of administration and the duration of the study (2-4 weeks; Table IV). Additionally, it also depends upon the species that have been included in the study as Apo E-/- mice established vascular endo- thelial dysfunction within 12 weeks of orally adminis- tering low dose of nicotine (0.1 mg/mL) (Qin et al., 2020). Though a high dose is used for the shorter duration studies, a high dose is associated with mor- tality. Thus, it may be suggested that small and repeti- tive doses should be chosen for chronic studies. Arsenic-induced The endothelial cells of the aortic arch of the experimen- tal rats exposed to arsenic-contaminated drinking water for 3 months at the dose of 10 or 50 mg/L are found to be seriously damaged (Guo et al., 2020). The levels of apoptotic factors, vWF, iNOS are elevated, while the level of PEDF (pigment epithelial-derived factor) which helps in maintaining endothelial function is decreased (Guo et al., 2020). Arsenic exposure leads to endothelial cell damage due to the release of apoptotic caspase-3. The detrimental role of arsenic is further supported by a study that reported that after 90 days of consecutive exposure to 100 ppm arsenic through drinking water, rats are found to have increased levels of adhesion molecules, cytokines, and inflammatory mediators while reduced levels of eNOS, iNOS mRNA expression, NO production which leads to vascular endothelial dysfunction-associated cardiovascular disorders (Kesa- van et al., 2014). Arsenic has also been noted to be involved in the activation of NADPH oxidase that tends to generate ROS/RNS in the blood vessels ultimately destroying its innermost layer (Ellinsworth, 2015). The detrimental role of arsenic has been further confirmed by the studies stating that exposure to arsenic for 2 weeks at a dose of 1.5 mg/kg relatively increases the expression of TNF-α, ROS/RNS which worsens the vascular endothelial dysfunction (Kaur et al., 2010; Jyoti et al., 2016). Histopathology studies from Wistar rats exposed to arsenic revealed that arsenic exposure is associated with agglutination of erythrocytes followed by infiltration of mononuclear cells, cytoplasmic swell- ing along morphological changes in nuclei of aortic endothelial cells (Guo et al., 2019b). Observed data from different studies in Table V express that exposure to arsenic at different doses ranging from 2-50 mg/L for 3- 6 months via drinking water is a widely used model for chronic study while the exposure through 100 mg/L arsenic in drinking water for 90 consecutive days is an alternative study with relevant alterations in biomar- kers. As high doses selected for short-term studies are associated with increased mortality. Therefore, low doses selected for long-term chronic studies are prefer- ed to reduce the mortality and toxicity index. Adminis- tration of 1.5 mg/kg of arsenic through intraperitoneal route for 2 weeks is preferred for short-term study. Bisphenol-A-induced An industrial chemical, bisphenol-A, is an endocrine imitating chemical that hampers the normal physio- logy. Bisphenol-A exposure to the animal (Wild-type CD1 mice) is associated with increased oxidative stress and it contributes to worsening vascular endothelial functioning by mediating the release of inflammatory mediators, up-regulating M-1 macrophage, and activa- ting CAM-KII. Activation of CAM-KII is further associ- ated with the release of apoptotic and necrotic factors which damages endothelial cells of blood vessels (Reventun et al., 2020). Thus, bisphenol-A is considered an important factor in the induction and progression of vascular endothelial dysfunction. Experimental rat model reveals that administered of bisphenol-A 0.1 mg/kg/day for 60 consecutive days, inhibits acetylcho- line-induced relaxation and also associated with NOS and COX blockage, increased levels of NADP+ with elevating the level of ROS/RNS resulting in impaired endothelial function. The model also states the involve- ment of prostanoids, increase levels of which results in vasoconstriction (Friques et al., 2020). It is worthwhile to note that administration of bisphenol-A through contaminated drinking water (4 nM to 400 µM) for 30 days to CD11 mice is found to increase Ang-II expre- ssion which uncouples eNOS from its co-factors like FMN, BH-4, promoting oxidative stress. Wistar rats exposed to bisphenol-A at a dose of 35 mg/kg via oral route for long-term study (60 days) decrease acetylcho- line-induced relaxation by increasing oxidative stress and lipid peroxidation (Rameshrad et al., 2018). In addition, the concentration of calcium/calmodulin- 72 Bangladesh J Pharmacol 2021; 16: 65-83 dependent protein kinase II α in 10 nM bisphenol-A- treated CD11 mice increases in aortic endothelial cells when assessed by microarray analysis which increases the generation of ROS/RNS (Saura et al., 2014). To summarize, bisphenol-A is continuously administered for at least 4 weeks to induce vascular endothelial dys- function, which may be extended to 16 weeks depen- ding upon the species to species and route of adminis- tration. Wild-type CD1 mice exposed to different doses ranging from 4 nM to 400 μM of bisphenol-A in the drinking shows the clinical signs of vascular endothelial dysfunction after 30 days. On the other hand, 35 mg/ kg/day orally for 2 months induced vascular endothe- lial dysfunction in Wistar rats, suggesting that a low dose is sufficient for genetically modified mice as com- pared to Wistar rats (Table VI). Hypertension Hypertension is one of the independent contributing risk factors for increasing vascular endothelial dysfunc- tion and associated vital organ dysfunction in the initial stages, while the progressed vascular endothelial dys- function plays a crucial role in worsening hypertension therefore, it has been stated that hypertension and vascular endothelial dysfunction are interlinked. Hypertension alters the normal physiological balance between vasorelaxant and vasoconstrictor factors and stimulates the vascular endothelial cells to release the vasoactive component like Ang-II, inflammatory cyto- kines, adhesion molecules (CAM, VCAM) resulting in vasoconstriction, thrombosis, and coagulation. A study revealed that hypertension, as well as vascular endo- thelial dysfunction, is responsible for promoting athe- rosclerosis. The formation of atherosclerotic plaques interferes with the free flow of the blood (Taddei et al., 2001). A) Deoxycorticosterone induced Deoxycorticosterone acetate is a mineralocorticoid that maintains electrolyte and fluid balance. It is used expe- rimentally in animals to induce hypertension (Schenk and McNeill, 1992). Intramuscular administration of deoxycorticosterone on day 1 (20 mg/kg), day 14 (10 mg/kg) to dog (Ueno et al., 1988) shows results similar to that of rat exposed to deoxycorticosterone subcuta- neously at the dose of 50 mg/kg twice a week (Basso et al., 1985). Deoxycorticosterone subcutaneous injection at 20 (Han et al., 2019) or 50 mg/kg (Niazi et al., 2020) has shown hypertension-induced vascular endothelial dysfunction by decreasing eNOS bioavailability and altered vascular tone (Kubacka et al., 2019). Deoxycorti- costerone-induced hypertension is associated with vas- cular endothelial dysfunction by the generation of ROS/RNS in the blood vessels that hampers the normal physiological balance between vasoconstrictory and vasodilatory factors. In addition, administration of deoxycorticosterone is associated with increased expre- ssion of Ang-II and NADPH oxidase. Mitochondrial SIRT-3 and SIRT-6 are deacetylase pro- teins that are expressed in cardiomyocytes and play a crucial role in regulating metabolic and antioxidant function. Interestingly, in deoxycorticosterone-induced Table V Arsenic-induced vascular endothelial disorders Species Dose and route Duration Pathways Altered biomarkers Reference Male Wistar rats 2, 10, and 50 mg/L, orally ad libitum 3-6 months ↓ pigment epithelium-derived factor ↑ protein levels of Fas, FasL, P53, and phospho-p38 ↑ ROS/RNS ↓ serum nitric oxide, von Wil- lebrand factor, and nitric oxide synthase Guo et al., 2019a; Guo et al., 2020 Male Wistar rats 100 mg/L, orally ad libitum 90 con- secutive days ↓ acetylcholine induced relaxation, aortic eNOS at the levels, NO pro- duction ↑ production of pro-inflammatory mediators (IL-1β, IL-6, MCP-1, VCAM, ICAM) and serum C- reactive protein ↑ phenylephrine ↑ eNOS and iNOS mRNA ex- pression ↓ NO bioavailability and produc- tion Kesavan et al., 2014 Wistar rats of either sex 1.5 mg/kg/ day, intraper- itoneally 2 weeks ↑ TNF-α ↓ l-arginine converting enzyme ↑ oxidative stress, TBARS abrogated acetylcholine-induced vasorelaxation ↓ serum nitrite/ nitrate concen- tration, glutathione level Kaur et al., 2010 Wistar rats of either sex 1.5 mg/kg/ day, intraper- itoneally 2 weeks ↑ TNF-α ↓ l-arginine converting enzyme ↑ oxidative stress, super oxides ↓ eNOS expression, ↓ serum nitrite/ nitrate concen- tration, glutathione level Jyoti et al., 2016 Bangladesh J Pharmacol 2021; 16: 65-83 73 hypertensive mice, the expression of SIRT-3 and SIRT-6 is noted to be depleted which elevates SOD2 acetyla- tion, caspase-I, Nf-KB activity, VCAM, ICAM and MCP1 levels that are responsible for ROS/RNS gena- ration leading to vascular endothelial dysfunction and associated cardiovascular disorders (Dikalova et al., 2020). A novel blood pressure regulator GATA-5 also expressed through SIRT-6 by inhibiting Nkx-3 trans- cription. Hypertension induced by deoxycorticosterone is also associated with increased systolic blood pre- ssure, decreased NO levels in plasma and increased endoplasmic reticulum stress which elevates GRP78, IP3R1 and EGFR levels (Guo et al., 2019a). B) Monocrotaline-induced Monocrotaline is a macrocyclic pyrazolidine alkaloid obtained from Crotalaria spectabilis associated with proli- ferative vasculitis, remodelling of pulmonary vessels, endothelial dysfunction and oxidative stress. A single administration (60 mg/kg) of monocrotaline induces pulmonary vascular syndrome in animal model within 2-3 weeks (Li et al., 2014). Monocrotaline directly contri- butes to causing pulmonary hypertension by increasing the ROS/RNS generation and accumulation which results in vascular endothelial dysfunction (Steven et al., 2017). Monocrotaline-induced vascular endothelial dysfunction on a single administration via subcuta- neous route influences the normal physiology and acts by decreasing the levels of PPAR-γ, PI3K-Akt, and elevating the levels of inflammatory cytokines, Ang-II and adhesion molecules. These pathways, directly and indirectly, mediates the generation and accumulation of ROS/RNS which tends to decrease acetylcholine-indu- ced vasorelaxation and alters the bioavailability of eNOS leading to the loss of vascular tone, integrity and free flow of the blood (Li et al., 2014). Monocrotaline is responsible for apoptosis of the endothelial cells as it decreases the anti-apoptotic factors (Sahara et al., 2012). C) Ethinyl estradiol-induced Ethinyl estradiol is one of the major components found in birth controlling pills but is also associated with the risk of the blood clot which can further lead to cardio- vascular disease including stroke, hypertension and high cholesterol, which stimulates endothelial cells to release vasoactive components (Balakumar et al., 2007). The combined pill increases the blood pressure, uric acid, C-reactive proteins, PAI-1 and activates the expre- ssion of RAAS (angiotensin converting enzyme, ATR’s, Ang-II) as well as increases the level of pro-infla- mmatory mediators. A study stated that the ethinyl estradiol-treated experimental model reverses the relaxation to acetylcholine. The risk of hypertension in ethinyl estradiol-treated rats is accompanied by endo- thelial degradations and elevated levels of proinfla- mmatory factors and RAAS (Olatunji et al., 2016). The administration of ethinyl estradiol is also considered as a factor for premature atherosclerosis, thrombogenesis and causes change in the endothelial structure and its function. D) Spontaneous hypertensive rats Spontaneous hypertensive rat is the genetic laboratory hypertensive animal model prepared by inbreeding of Wistar-Kyoto rats with elevated blood pressure. The spontaneous hypertensive rat is characterized by vari- ous vascular disorders. Spontaneous hypertensive rat tends to increase the expression of angiotensin and mediates the release of inflammatory factors worsening the integrity of the vascular endothelial altering the Table VI Bisphenol A-induced vascular endothelial disorders Species Dose and route Duration Pathways Altered biomarkers Reference Wild-type CD1 mice ≤50 mg/kg/ day (a low dose) ethanol dis- solved-BPA in drinking water 4, 8, and 16 weeks ↑ expression of inflammatory cyto- kines, TNF-α, RIP-3, caspase-I activating CAM-KII ↓ PARP expression ↑ oxidative stress ↓ eNOS expression, TBARS abrogated acetylcholine-induced vasorelaxation ↑ lipid peroxidation, decreased glutathione (GSH) levels Reventun et al., 2020 Male albino Wistar rats 35 mg/kg/ day orally 60 days ↑ vascular cell adhesion molecule ↑ lipid peroxidation ↑ ROS/RNS, oxidative stress ↓ acetylcholine-induced relaxa- tion Rameshrad et al., 2018 Male Wistar rats 0.1 mg/kg/ day orally 60 days ↑ ROS, NADPH oxidase ↑ prostanoids-mediated vasocon- striction ↓ NO impaired acetylcholine-induced relaxation Friques et al., 2020 Wild-type CD1 mice 4 nM to 400 μM in drink- ing water 30 days ↑ arterial angiotensin II ↑ NADPH oxidase impairment of acetylcholine relaxation significant superoxide and per- oxynitrite accumulation Saura et al., 2014 74 Bangladesh J Pharmacol 2021; 16: 65-83 vascular tone. Spontaneous hypertensive rat is govern- ed by increase ROS/RNS production while it is repor- ted to show altered vasorelaxation towards acetylcho- line (Chi et al., 2017). Taken together, it may be concluded that deoxycorticos- terone and monocrotaline are gaining more attention by researchers for the induction of vascular endothelial dysfunction in males. Both models are associated with increased ROS generation and reduction in NO level. However, deoxycorticosterone-induced vascular endo- thelial dysfunction has been correlated with the slow pathogenetic mechanism as deoxycorticosterone (20 mg/kg, subcutaneously) administration once weekly took 12 weeks to induce vascular endothelial dysfunc- tion. On another hand, a single intravenous injection of monocrotaline in doses ranging from (30-60 mg/kg) takes 2-6 weeks to induce experimental vascular endothelial dysfunction. Among hypertension-associa- ted vascular endothelial dysfunction models, ethinyl estradiol in combination with norgestrel is considered as the gold standard for evaluation of vasoprotective potential of an agent against vascular endothelial dys- function in females. For short-term studies, especially where the agent is evaluated for its potential to modu- late the RAAS pathway, spontaneous hypertensive rat is preferred (Table VII to IX). PM-2.5 induced Tiny and fine inhalable elements of diameter <2.5 µm present in air is one of the most common and most dangerous air pollutants responsible for causing severe health problems including vascular complications. Acute and chronic exposure to PM-2.5 for short or long duration through inhalation not only affects lungs but after reaching to blood vessels can cause vascular endo- thelial dysfunction and can lead to cardiovascular disorders. PM-2.5 increases the vascular permeability and can alter the barrier function of blood vessels. A study demonstrated that PM-2.5 instigates the release of Ang-II, angiotensin converting enzyme and AT-1R in the blood vessels which subsequently increases oxida- tive stress (ROS/RNS) by enhancing the release of pro- inflammatory mediators (Qimuge et al., 2019). In addi- tion, PM-2.5 exposed animal model reveals a negative co-relation between eNOS, acetylcholine and TNF-α; as the levels of TNFα in PM-2.5-induced animals are elevated while the acetylcholine-induced vasorelaxation is altered due to the decreased levels of eNOS. It is worthwhile to note that PM-2.5 associated accumula- tion of adhesion molecule in the blood vessels creates an imbalance between vasoconstricting and vasorelax- ing factors (Liang et al., 2019) that further worsen the vascular integrity. Further, PM-2.5 exposure induces the expression of NRF-2, HO-1 that enhances the oxida- tive stress ultimately, alters the blood vessel integrity. Moreover, eosin and hematoxylin staining of rat aorta revealed that PM-2.5 also increases vascular permea- bility resulting in interstitial edema and vascular inju- ries due to the accumulation of inflammatory cells. A decrease in the aortic lumen diameter and an increase in thickness of the endothelial layer is also observed in PM 2.5-treated rat aorta (Dai et al., 2017). Summarized data (Table X) suggest that intratracheal instillation of PM-2.5 from 1.8-16.2 mg/kg is in practice to induce experimental vascular endothelial dysfunction. Intra- Table VII Deoxycorticosterone-induced vascular endothelial disorders Species Dose and route Duration Pathways Altered biomarkers Reference Male Wistar rats 50 mg/kg in corn oil, sub- cutaneous once a week for 5 weeks COX and NO blockage ↑ prostanoid secretion ↑ NADPH oxidase subunit p22 ↑ phenylepinephrine-induced contraction ↓ serum/aortic NOS and eNOS Niazi et al., 2020 Male Wistar albino rats 20 mg/kg, subcutaneous 12 weeks Twice a week ↑ GRP78, IP3R1 and EGFR, ↑ expressions of SERCA2 and Bcl2in vessels ↓ serum/aortic NOS and eNOS, acetyl-induced vasorelaxation Han et al., 2019 Male Wistar rats 20 mg/kg in olive oil, subcutaneous twice weekly for 12 weeks. ↑ interleukin 6, C-reactive protein, inflammation mediators ↑ inflammatory cell infiltration, fibrosis and arteriosclerotic alter- ations ↓ endothelial integrity, NOS activity and bioavailability Kubacka et al., 2019 Dog day 1 (20 mg/ kg, intramus- cular) day 14 (10 mg/kg, intramuscu- lar) Day 1 and day 14 altered Ang-II, vasopressin activity tachycardia failed vasodilatory responses ↑ intracellular Ca+2 Ueno et al., 1988 Male Wistar rats 50 mg/kg subcutaneous Twice a week altered Ang-II, vasopressin activity tachycardia failed vasodilatory responses ↑ intracellular Ca+2 Basso et al., 1985 Bangladesh J Pharmacol 2021; 16: 65-83 75 tracheal instillation of PM-2.5 from 5.4 mg/kg to Spra- gue-Dawley rat seems to be the most preferable model. Monosodium glutamate-induced Monosodium glutamate (ajinomotto) acts as a neuro- transmitter that affects the physiology of the body, lead- ing to various disorders (Niaz et al., 2018). Excessive consumption of ajinomotto is associated with vascular endothelial dysfunction by increasing the oxidative stress along with significant elevation of matrix metalo- protinase-1 and endothelin-1 levels (Abo Zeid et al., 2020). Injurious role of monosodium glutamate is confirmed as triglycerides, total cholesterol, LDL-C, TNF-α are found to be increased while NO levels are decreased in serum and aorta tissue homogenate. Decreased expression of Akt, PI3K, and PGI2 are also found to be the governing factors of vascular endo- thelial dysfunction (Leao et al., 2019). Excessive con- sumption of monosodium glutamate is reported to increase the ROS generation building the stress on vas- cular endothelial by inducing the release of inflamma- tory cytokines that finally resulting in induction and progression of vascular endothelial dysfunction (Lobato et al., 2011). Monosodium glutamate-treated rat aortic endothelium showed the thickening of tunica media along with deposition of fats that reduces the lumen of the aorta. In addition, increased inflammatory media- tors are also observed (Abo Zeid et al., 2020). Complied data from different studies in Table XI reflect no variation in dose of monosodium glutamate to induce vascular endothelial dysfunction irrespective of age of the animals. All the models showed common patho- genetic pathways for vascular endothelial dysfunction induction and progression. Uric acid-induced Excessive level of uric acid to severe disorders like gout, diabetes, kidney stones, etc (Fathallah-Shaykh et al., 2013) along with vascular endothelial dysfunction, which is one of the most serious condition which can lead to different cardiovascular disorders. Hyperuri- cemia is often associated with increased oxidative stress, lipid peroxidation and decreased levels of SOD, nitric oxides, glutathione, thus play a crucial role in induction and progression of vascular endothelial dys- function. In addition, uric acid-treated animal model reveals that hyperuricemia is also associate with eleva- tion of increased inflammatory mediators, chemokines, Table VIII Monocrotaline-induced vascular endothelial disorders Species Dose and route Duration Pathways Altered biomarkers Reference Male Wistar rats 30, 40 and 60 mg/kg single intravenous 2, 4 and 6 weeks i.e. 14th, 28th and 43rd day ↑ endothelial dysfunction ↑ ROS/RNS ↑ endothelin-1 activity ↑ pulmonary wall thickening ↓ NO’s ↑ uncoupling of eNOS ↑ adhesion molecules (ICAMS/ VCAMS) Steven et al., 2017 Male Spra- gue Dawley rat 60 mg/kg single subcutaneous single- dose ↓ expression of PPARᵞ ↓ PI3K-Akt ↓ eNOS ↓ vasorelaxation ↑ vascular remodelling ↑ ROS/RNS ↓ acetylcholine-induced endothe- lium-dependent vasorelaxation of pulmonary arteries Li et al., 2014 Sprague- Dawley rats 60 mg/kg ↑ RVSP ↑ up-regulation of caspase-III ↓ PI3K/Akt ↓ anti-apoptotic factors (BCl-2) Down-regulated eNOS expres- sion ↑ ROS Sahara et al., 2012 Table IX Ethinyl estradiol-induced vascular endothelial disorders Species Dose and route Duration Pathways Altered biomarkers Reference Female Sprague- Dawley rats combination of 0.1 μg ethinylestradiol and 1.0 μg norgestrel orally 6 weeks/ day ↑ ACE, Ang-II and AT-R expression ↑ contractile responses to phenylephrine, impaired acetylcholine-induced relaxation ↓ eNOS and NO activity ↑ hypertension ↑ uric acid, C- reactive protein ↑ PAI-1 Olatunji et al., 2016 1.0 μg ethinylestra- diol and 10.0 μg norgestrel 76 Bangladesh J Pharmacol 2021; 16: 65-83 cytokines and adhesion molecules like VCAM (Oya- bambi et al., 2020). Further, the expression of various pathways like Nf-Kb, TNF-α enhanced due to accu- mulation of uric acid. Moreover, uric acid exposure also activates the RAAS system which increases the expression of Ang-II, angiotensin converting enzyme and angiotensin II receptor type 1 which contributes in causing vascular endothelial dysfunction (Balakumar et al., 2008c). Animal species, dose & route, duration along with the associated pathways have been summarized in Table XII. Homocysteine-induced Excessive levels of homocysteine, an independent risk factor, contributing to cause vascular endothelial dys- function and is also associated with cardiovascular system disorders (Moretti and Caruso, 2019; Esse et al., 2019). Homocysteine quenches the level of NO by reducing the bioavailability and uncoupling NOS from its co-factors (Kumar et al., 2017; Ji et al., 2021). Homo- cysteine-induced vascular endothelial disorder is asso- ciated with increased oxidative stress which further instigates the release of pro-inflammatory, apoptotic and pro-thrombotic factors while down-regulates VEGF, p-tyr-VEGFR2 and phospho-focal adhesion kinase (Tyr397) (Lan et al., 2011; Wang et al., 2019). In addition, phenylepinephrine-induced vasoconstric- tion and vWf is also noted to be increased. Hyper- homocysteinemia also tends to increase the expression of Ero-1 (endoplasmic reticullum oxidoreductin) which tends to trigger oxidative stress by mediating the generation of ROS/RNS. Homocysteine increases apoptosis by enhancing the release of caspase-3 and Bax (Ren et al., 2016). Animal species, dose & route, duration along with the associated pathways have been summarized in Table XIII. High fat diet-induced Obesity is a widespread metabolic disorder which serves as a risk factor for complicating various micro- and macro-vascular diseases. Different studies stated that consumption of high fat diet is associated with altered NO’s function as a result leading to vascular endothelial dysfunction. It is considered as the major cause of morbidity and mortality (Zhao et al., 2020). Increased level of LDL’s and v-LDLs in the blood vessels leads to the formation of atherosclerotic Table X PM 2.5-induced vascular endothelial disorders Species Dose and route Duration Pathways Altered biomarkers Reference Sprague- Dawley rats 1.8, 5.4 and 16.2 mg/kg intratracheal instillation every 3 days for 30 days ↑ expression of JAK/STAT signalling pathway ↑ expression of TLR4/p38/NF-κB pathway ↑ arterial thrombus formation ↑ inflammatory mediators (IL-6, VCAM, ICAM, MCP, CRP) disruptive fibrinolysis Liang et al., 2019 Sprague- Dawley rats once every 3 days for 28 days ↑ phosphorylation of STAT3 up-regulation of miR-21 inhibits TIMP3/MMP9 signalling alteration in the barrier func- tion of the vascular endothe- lium Dai et al., 2017 Table XI Monosodium glutamate-induced vascular endothelial disorders Species Dose and route Duration Pathways Altered biomarkers Reference New born Wister Albi- no rats 4 mg/g orally 14 days ↑ expression of endothelin-1 ↑ expression of MMP-1 ↑ ROS/RNS ↑ NADPH oxidase ↑ NOX-4 expression ↓ eNOS and NO activity ↑ inflammatory response ↑ VSMC Abo Zeid et al., 2020 New born Wistar rats 4.0 g/kg sub- cutaneous injection second to the sixth day after birth ↑ levels of LDL’s, vLDL’s and triglycerides ↑ ROS/RNS ↑ phenylepinephrine-induced vasocon- striction ↓ eNOS levels loss integrity of vascular endothelium Lobato et al., 2011 Male Wistar rats 4.0 g/kg sub- cutaneous injection first 5 days ↓ Akt/ PI-3K expression ↑ ROS/RNS ↑ cholesterol ↑ thrombosis, endothelin-1 ↑ platelet adhesion and aggregation ↓ acetylcholine-induced vasorelaxation ↓ expression of PGI2, NO Leao et al., 2019 Bangladesh J Pharmacol 2021; 16: 65-83 77 Table XII Uric acid-induced vascular endothelial disorders Species Dose and route Duration Pathways Altered biomarkers Reference Male Wistar rats 150 mg/kg/ day intraperi- tonially 3 weeks ↑ generation of ROS/RNS ↓ acetylcholine-induced endothelium- dependent relaxation ↑ activation of NADPH oxidase ↑ xanthine oxidase up-regulate the expression of various fibroblast growth factor, tumor necro- sis factor and plasminogen activator inhibitor-1 ↑ mononuclear leukocyte adhesion ↑ expression of adhesion molecules such as VCAM-1 and ICAM ↓ aortic and serum nitrite/nitrate, ↑ aortic superoxide anion genera- tion, ↓ acetylcholine-induced endotheli- um-dependent relaxation impairing endothelial integrity, inducing vascular oxidative stress ↑ serum TBARS down-regulating the expression of eNOS impairing endothelial integrity Balakumar et al., 2008c; Female Wistar rats High salt feed consisting of 8 % NaCl– plasma uric acid level rise to 15 U/mL 6 weeks ↑ expression of adhesion molecules such as VCAM-1 and ICAM ↓ aortic and serum nitrite/nitrate, ↑ aortic superoxide anion genera- tion Oyabambi et al., 2020 plaques which interfere with the free flow of blood. High concentration of fat is responsible for stimulating the vascular endothelial cells to release vasoactive substances, thrombotic factors and decreases vasodila- tory substances (NO, PGI2). High cholesterol increases the lipid peroxidation of LDL, which tends to increase the oxidative stress by generating large amounts of ROS/RNS, alters the expression of PI3K-Akt, eNOS and SIRT pathways which leads to the loss of vascular tone, integrity, arginase activity (Huang et al., 2018). Male CDH5 CreERT2 Ftoflox/flox mice fed on 60% high fat diet for the duration of 8 weeks showed obesity with increased level of cholesterol which directly and indirectly lead to increase the oxidation of LDL’s or vLDL’s which gets accumulated in the blood vessels resulting in the formation of atherosclerotic plaques and narrowing the lumen of the blood vessels (Kruger et al., 2020). Apart from the mice or rats, male hybrid flanders rabbits is employed to induce obesity and subsequent vascular endothelial dysfunction with standard rabbit chow added with 18% of fats (10% corn oil + 8% lard) for 6 weeks (Alarcon et al., 2018). Numerous studies used different percentage of fat to induce obesity with different composition, suggesting that there is huge scope to formulate their high fat diet to induce obesity related vascular endothelial dys- function. Glucocorticoid-induced Glucocorticoid (play crucial role on metabolism and glucocorticoid analogues like prednisolone, dexame- thasone) is also widely employed for reducing the inflammation, fight certain cancers, autoimmune disorders but due to their severe effects on vasculature the use is limited (Yang and Zhang, 2004). Excessive levels of glucocorticoids are associated with vaso- constriction, altered capillary permeability, Atheros- clerosis and increased blood pressure i.e. hypertension which overall results in vascular endothelial dysfunc- tion (Ross and Linch, 1982). Glucocorticoids has been noted to increase the superoxide levels which led to the uncoupling of eNOS from its co-factors resulting in NO’s dysfunctioning (Akaike and Matsumoto, 2007). In addition, mice treated with dexamethasone (0.1-3 mg/kg) revealed that glucocorticoid involves down- regulation of eNOS, down-regulation of cationic amino acid transporter-1, and 3) and generation of reactive oxygen species for induction of vascular abrasion (Schafer et al., 2005). It is worthwhile to note that endothelium-dependent vasodilation in response to acetylcholine (0.1-10 µM) is reduced by dexametha- sone in a dose-dependent fashion (Schafer et al., 2005). Hypochlorite-induced Hypochlorite is chlorine ox-anion widely explored for it disinfectant and exposure to hypochlorite can cause skin or eye irritation, severe injuries, burns etc. Hypochlorite itself is a superoxide mediator which is responsible for inducing oxidative stress (Radovits et al., 2013). This generated oxidative stress is responsible for uncoupling the eNOS from its co-factors altering the NO’s bioavailability. A study also stated that hypochlorite intensifies the NADPH oxidase activity leading to overproduction of ROS/RNS molecules which creates an imbalance between antioxidant and free radicle resulting in vascular endothelial dysfunc- tion (Tian et al., 2017). Pre-treatment with hypochlorite results in impaired endothelial-dependent vasorelaxa- tion and acetylcholine-induced vasorelaxation and increases the formation of atherosclerotic plaques 78 Bangladesh J Pharmacol 2021; 16: 65-83 Table XIII Homocysteine-induced vascular endothelial disorders Species Dose and route Duration Pathways Altered biomarkers Reference Male Sprague Dawley rats 3% methionine (w/w) in feed 8 weeks ↑ endothelin-1, Ang-II ↑ TXA-2 ↓ PGI-2 ↑ expression of RAAS rapid decomposition of NO ↑ thrombosis inhibition of NO production and eNOS Ji et al., 2020 Male Wistar rats L-methionine 1.7 g/kg/day, orally 32 days ↑ phenylepinephrine-induced constriction ↑ ROS/ RNS ↓ NO bioavailability ↓ SOD, GSH. CAT attenuated vasorelaxation impaired eNOS activity ↑ TBARS Kumar et al., 2017 Male Sprague- Dawley rats L-methionine 1 g/kg/day intragastricly 4 weeks ↓ PI3K, Akt ↑ oxidative stress ↓ NO bioavailability down-regulating the expression of eNOS impairing endothelial integrity Lan et al., 2011 Male Sprague- Dawley rats L-methionine by 1 g/kg/ day intra- gastricly 4 weeks ↑ apoptotic factors, and apopto- sis of endothelial cells ↑ caspase-3 , bax ↓ Akt expression ↑ vascular injury impaired endothelium-derived vasorelaxation ↓ eNOS activity ↓ NO bioavailability Ren et al., 2016 (Ding et al., 2014). Isolated aorta of rat exposed to hypochlorite at the dose of 100-400 µM is found to be associated with decreased acetylcholine-induced vasorelaxation. This alteration in vascular tone is due to eNOS uncoupling and decreased the NO bioavaila- bility (Tian et al., 2017). In addition, the exposed aorta is found to associated with decreased PARP expre- ssion, increased lipid peroxidation, release of infla- mmatory mediators and increased DNA damage resulting in worsening of vascular endothelial dysfun- ction (Radovits et al., 2013). Endotoxin-induced Lipopolysaccharide is one of the most common endo- toxins formed by covalent bond between lipid A and polysaccharide. It is found in the outer layer of the Gram negative bacteria (Lynn and Golenbock, 1992). Endotoxins stimulate the endothelial cells to activate fibroblasts (Echeverría et al., 2014) and enhance the release of pro-inflammatory cytokines, and increase oxidative stress burst which result in causing fever, inflammation, aseptic shock and death. Lipo-polysa- ccharide (1 mg/kg intraperitoneal once) to mice is noted to be associated with increased mRNA levels of IL-6, and IL-8 (Huang et al., 2019). While single intra- venous administration of E. coli 15 mg/kg established vascular endothelial dysfunction in rats within 6 hours (Balakumar et al., 2007). Activation of fibroblast leads to endothelial fibrosis which tends to alter the NO’s bioavailability leading to vascular endothelial dysfun- ction especially pulmonary vascular injury (Chuai- phichai et al., 2016; Huang et al., 2019). Overectomy/estrogen deficiency-induced Oestrogen, an endocrine hormone has been noted to regulate eNOS activity which helps to release suffi- cient amount of NO for the vasodilation of the vessel. Low levels of oestrogen in post-menopausal female is one of the causes for increased risk of cardiovascular disease. Low levels of oestrogen up-regulates RAAS system which results in hypertension and is also responsible for atherosclerotic plaque formation while it also increases the concentration of free radicles which activates endothelial cells to cause vascular endothelial dysfunction (Wassmann et al., 2001). Thus, to establish the correlation between the hypertension, oestrogen deficiency associated vascular endothelial dysfunction, overiectomized spontaneously hyper- tensive female rats are considered to be gold standard and are widely used to evaluate the therapeutic agents for their potential to manage the vascular complica- tions in menopausal condition. Conclusion To understand complex pathogenesis and to develop a new therapeutic alternative for treating vascular endo- thelial dysfunction animal models are widely used. Continued utilization of these experimental models simulating human vascular endothelial dysfunction, particularly those that combine other clinically rele- vant comorbidities like obesity, nicotine intake, hyper- uricemia or hypercholesterolemia, may open a new vista in development of effective strategies to address the vascular complications. Nevertheless, a restrained methodology is mandatory while experimental find- ings in these models are extrapolated to human vas- cular endothelial dysfunction. Bangladesh J Pharmacol 2021; 16: 65-83 79 Financial Support Self-funded Conflict of Interest Authors declare no conflict of interest References Abo Zeid AA, Rowida Raafat I, Ahmed AG. Berberine alleviates monosodium glutamate induced postnatal meta- bolic disorders associated vascular endothelial dysfunction in newborn rats: Possible role of matrix metalloproteinase- 1. Arch Physiol Biochem. 2020; 19: 1-12. Adel H, Taye A, Khalifa MM. Spironolactone improves endothelial dysfunction in streptozotocin-induced diabetic rats. Naunyn Schmiedebergs Arch Pharmacol. 2014; 387: 1187-97. Akaike M, Matsumoto T. Glucocorticoid-induced reduction in NO bioavailability and vascular endothelial dysfunction. Clin Calcium. 2007; 17: 864-70. Alarcon G, Roco J, Medina M, Medina A, Peral M, Jerez S. High fat diet-induced metabolically obese and normal weight rabbit model shows early vascular dysfunction: Mechanisms involved. Int J Obes (Lond). 2018; 42: 1535-43. Azemi AK, Mokhtar SS, Rasool AHG. Clinacanthus nutans leaves extract reverts endothelial dysfunction in type 2 diabetes rats by improving protein expression of eNOS. Oxid Med Cell Longev. 2020; 2020. Babacanoglu C, Yildirim N, Sadi G, Pektas MB, Akar F. Resveratrol prevents high-fructose corn syrup-induced vascular insulin resistance and dysfunction in rats. Food Chem Toxicol. 2013; 60: 160-67. Baig MA, Panchal SS. Streptozotocin-induced diabetes mellitus in neonatal rats: An insight into its applications to induce diabetic complications. Curr Diabetes Rev. 2019; 16: 26-39. Balakumar P, Chakkarwar VA, Kumar V, Jain A, Reddy J, Singh M. Experimental models for nephropathy. J Renin Angiotensin Aldosterone Syst. 2008a; 9: 189-95. Balakumar P, Chakkarwar VA, Singh M. Ameliorative effect of combination of benfotiamine and fenofibrate in diabetes- induced vascular endothelial dysfunction and nephro- pathy in the rat. Mol Cell Biochem. 2009; 320: 149-62. Balakumar P, Jindal S, Shah DI, Singh M. Experimental models for vascular endothelial dysfunction. Trends Med Res. 2007; 2: 12-20. Balakumar P, Kaur T, Singh M. Potential target sites to modulate vascular endothelial dysfunction: Current pers- pectives and future directions. Toxicology 2008b; 245: 49- 64. Balakumar P, Sharma R, Singh M. Benfotiamine attenuates nicotine and uric acid-induced vascular endothelial dysfunction in the rat. Pharmacol Res. 2008c; 58: 356-63. Basso N, Ruiz P, Kurnjek ML, Cannata MA, Taquini AC. The brain renin-angiotensin system and the development of DOC-salt hypertension. Clin Exp Hypertension. 1985; A7: 1259-68. Brahmanaidu P, Uddandrao VVS, Sasikumar V, Naik RR, Pothani S, Begum MS, Rajeshkumar MP, Varatharaju C, Meriga B, Rameshreddy P, Kalaivani A, Saravanan G. Reversal of endothelial dysfunction in aorta of streptozo- tocin-nicotinamide-induced type-2 diabetic rats by S- allylcysteine. Mol Cell Biochem. 2017; 432: 25-32. Capellini VK, Baldo CF, Celotto AC, Batalhão ME, Cárnio EC, Rodrigues AJ, Evora PR. Oxidative stress is not associated with vascular dysfunction in a model of alloxan-induced diabetic rats. Arq Bras Endocrinol Metabol. 2010; 54: 530- 39. Carvalho C, Santos RX, Cardoso S, Correia S, Oliveira PJ, Santos MS, Moreira PI. Doxorubicin: The good, the bad and the ugly effect. Curr Med Chem. 2009; 16: 3267-85. Chakkarwar VA. Fenofibrate attenuates nicotine-induced vascular endothelial dysfunction in the rat. Vascul Pharmacol. 2011; 55: 163-68. Chi L, Hu X, Zhang W, Bai T, Zhang L, Zeng H, Guo R, Zhang Y, Tian H. Adipokine CTRP6 improves PPARγ activation to alleviate angiotensin II-induced hypertension and vascular endothelial dysfunction in spontaneously hypertensive rats. Biochem Biophys Res Commun. 2017; 482: 727-34. Chuaiphichai S, Starr A, Nandi M, Channon KM, McNeill E. Endothelial cell tetrahydrobiopterin deficiency attenuates LPS-induced vascular dysfunction and hypotension. Vascul Pharmacol. 2016; 77: 69-79. Clayton ZS, Brunt VE, Hutton DA, VanDongen NS, D'Alessandro A, Reisz JA, Ziemba BP, Seals DR. Doxo- rubicin-induced oxidative stress and endothelial dysfunc- tion in conduit arteries is prevented by mitochondrial- specific antioxidant treatment. JACC Cardio Oncol. 2020; 2: 475-88. Dai J, Chen W, Lin Y, Wang S, Guo X, Zhang QQ. Exposure to concentrated ambient fine particulate matter induces vascular endothelial dysfunction via miR-21. Int J Biol Sci. 2017; 13: 868-77. Dikalova AE, Pandey A, Xiao L, Arslanbaeva L, Sidorova T, Lopez MG, Billings FT 4th, Verdin E, Auwerx J, Harrison DG, Dikalov SI. Mitochondrial deacetylase Sirt3 reduces vascular dysfunction and hypertension while Sirt3 deple- tion in essential hypertension is linked to vascular infla- mmation and oxidative stress. Circ Res. 2020; 126: 439-52. Ding Y, Zhang B, Zhou K, Chen M, Wang M, Jia Y, Song Y, Li Y, Wen A. Dietary ellagic acid improves oxidant-induced endothelial dysfunction and atherosclerosis: Role of Nrf2 activation. Int J Cardiol. 2014; 175: 508-14. Echeverría C, Montorfano I, Tapia P, Riedel C, Cabello- Verrugio C, Simon F. Endotoxin-induced endothelial fibro- sis is dependent on expression of transforming growth factors β1 and β2. Infect Immun. 2014; 82: 3678-86. El-Bassossy HM, Dsokey N, Fahmy A. Characterization of vascular complications in experimental model of fructose- 80 Bangladesh J Pharmacol 2021; 16: 65-83 induced metabolic syndrome. Toxicol Mech Methods. 2014; 24: 536-43. Ellinsworth DC. Arsenic, reactive oxygen, and endothelial dysfunction. J Pharmacol Exp Ther. 2015; 353: 458-64. Esse R, Barroso M, Tavares de Almeida I, Castro R. The con- tribution of homocysteine metabolism disruption to endo- thelial dysfunction: State-of-the-art. Int J Mol Sci. 2019; 20: 867. Fadini GP, Avogaro A. Cell-based methods for ex vivo evalua- tion of human endothelial biology. Cardiovasc Res. 2010; 87: 12-21. Fathallah-Shaykh SA, Cramer MT. Uric acid and the kidney. Pediatr Nephrol. 2014; 29: 999-1008. Friques AGF, Santos FDN, Angeli DB, Silva FAC, Dias AT, Aires R, Leal MAS, Nogueira BV, Amorim FG, Campag- naro BP, Pereira TMC, Campos-Toimil M, Meyrelles SS, Vasquez EC. Bisphenol A contamination in infant rats: Molecular, structural, and physiological cardiovascular changes and the protective role of kefir. J Nutr Biochem. 2020; 75: 108254. Guo J, Wang Z, Wu J, Liu M, Li M, Sun Y, Huang W, Li Y, Zhang Y, Tang W, Li X, Zhang C, Hong F, Li N, Nie J, Yi F. Endothelial SIRT6 is vital to prevent hypertension and associated cardiorenal injury through targeting Nkx3.2- GATA5 signalling. Circ Res. 2019a; 124: 1448-61. Guo X, Fu X, Liu X, Wang J, Li Z, Gao L, Li Y, Zhang W. Role of pigment epithelium-derived factor in arsenic-induced vascular endothelial dysfunction in a rat model. Biol Trace Elem Res. 2019b; 190: 405-13. Guo X, Liu X, Wang J, Fu X, Yao J, Zhang X, Jackson S, Li J, Zhang W, Sun D. Pigment epithelium-derived factor (PEDF) ameliorates arsenic-induced vascular endothelial dysfunction in rats and toxicity in endothelial EA. hy926 cells. Environ Res. 2020; 186: 109506. Hadi HA, Carr CS, Al Suwaidi J. Endothelial dysfunction: Cardiovascular risk factors, therapy, and outcome. Vasc Health Risk Manag. 2005; 1: 183-98. Han S, Bal NB, Sadi G, Usanmaz SE, Tuglu MM, Uludag MO, Demirel-Yilmaz E. Inhibition of endoplasmic reticulum stress protected DOCA-salt hypertension-induced vascular dysfunction. Vascul Pharmacol. 2019; 113: 38-46. Huang JP, Hsu SC, Li DE, Chen KH, Kuo CY, Hung LM. Resveratrol mitigates high-fat diet-induced vascular dys- function by activating the Akt/eNOS/NO and Sirt1/ER pathway. J Cardiovasc Pharmacol. 2018; 72: 231-41. Huang X, Zhu J, Jiang Y, Xu C, Lv Q, Yu D, Shi K, Ruan Z, Wang Y. SU5416 attenuated lipopolysaccharide-induced acute lung injury in mice by modulating properties of vas- cular endothelial cells. Drug Des Devel Ther. 2019; 13: 1763- 72. Ji B, Yuan K, Li J, Ku BJ, Leung PS, He W. Protocate- chualdehyde restores endothelial dysfunction in streptozo- tocin-induced diabetic rats. Ann Transl Med. 2021a; 9: 711. Ji XW, Lyu HJ, Zhou GH, Wu B, Zhu YY, Wu TH, Zhang F, Jin SN, Cho KW, Wen JF. Physcion, a tetra-substituted 9,10- anthraquinone, prevents homocysteine-induced endothe- lial dysfunction by activating Ca2+- and Akt-eNOS-NO signaling pathways. Phytomedicine 2021b; 81: 153410. Jyoti U, Kansal SK, Kumar P, Goyal S. Possible vasculopro- tective role of linagliptin against sodium arsenite-induced vascular endothelial dysfunction. Naunyn Schmiedebergs Arch Pharmacol. 2016; 389: 167-75. Kaur T, Goel RK, Balakumar P. Effect of rosiglitazone in sodium arsenite-induced experimental vascular endothe- lial dysfunction. Arch Pharm Res. 2010; 33: 611-18. Kesavan M, Sarath TS, Kannan K, Suresh S, Gupta P, Vijayakaran K, Sankar P, Kurade NP, Mishra SK, Sarkar SN. Atorvastatin restores arsenic-induced vascular dysfun- ction in rats: Modulation of nitric oxide signaling and inflammatory mediators. Toxicol Appl Pharmacol. 2014; 280: 107-16. Khitan Z, Kim DH. Fructose: A key factor in the development of metabolic syndrome and hypertension. J Nutr Metab. 2013; 2013. Kho MC, Lee YJ, Cha JD, Choi KM, Kang DG, Lee HS. Gastrodia elata ameliorates high-fructose diet-induced lipid metabolism and endothelial dysfunction. Evid Based Complement Alternat Med. 2014; 2014. Kruger N, Biwer LA, Good ME, Ruddiman CA, Wolpe AG, DeLalio LJ, Murphy S, Macal EH Jr, Ragolia L, Serbulea V, Best AK, Leitinger N, Harris TE, Sonkusare SK, Gödecke A, Isakson BE. Loss of endothelial FTO antagonizes obesity- induced metabolic and vascular dysfunction. Circ Res. 2020; 126: 232-42. Kshirsagar RP, Chouthe RS, Reddy GB, Bhardwaj DK, Diwan PV. Geraniol ameliorates endothelial dysfunction in strep- tozotocin-induced diabetic rats. J Pharm Res. 2017; 11: 1159 -65. Kubacka M, Zadrożna M, Nowak B, Kotańska M, Filipek B, Waszkielewicz AM, Marona H, Mogilski S. Reversal of cardiac, vascular, and renal dysfunction by non-quina- zoline α1-adrenolytics in DOCA-salt hypertensive rats: A comparison with prazosin, a quinazoline-based α1-adreno- ceptor antagonist. Hypertens Res. 2019; 42: 1125-41. Kumar BH, Reddy AR, Kumar JM, Bhardwaj DK, Diwan PV. Effects of fisetin on hyperhomocysteinemia-induced expe- rimental endothelial dysfunction and vascular dementia. Can J Physiol Pharmacol. 2017; 95: 32-42. Lan TH, Xu ZW, Wang Z, Wu YL, Wu WK, Tan HM. Ginse- noside Rb1 prevents homocysteine-induced endothelial dysfunction via PI3K/Akt activation and PKC inhibition. Biochem Pharmacol. 2011; 82: 148-55. Le Brocq M, Leslie SJ, Milliken P, Megson IL. Endothelial dysfunction: From molecular mechanisms to measurement, clinical implications, and therapeutic opportunities. Anti- oxid Redox Signal. 2008; 10: 1631-74. Leao VF, Ferreira LLDM, Melo CM, Bonfleur ML, da Silva LL, Carneiro EM, Raimundo JM, Ribeiro RA. Taurine supplementation prevents endothelial dysfunction and attenuates structural changes in aortas from hypothalamic obese rats. Eur J Nutr. 2019; 58: 551-63. Li H, Lu W, Cai WW, Wang PJ, Zhang N, Yu CP, Wang DL, Liu BC, Sun W. Telmisartan attenuates monocrotaline- induced pulmonary artery endothelial dysfunction Bangladesh J Pharmacol 2021; 16: 65-83 81 through a PPAR gamma-dependent PI3K/Akt/eNOS pathway. Pulm Pharmacol Ther. 2014; 28: 17-24. Li X, Gu J, Zhang Y, Feng S, Huang X, Jiang Y, Xia Y, Liu Y, Yang X. l-arginine alleviates doxorubicin-induced endothe- lium-dependent dysfunction by promoting nitric oxide generation and inhibiting apoptosis. Toxicology 2019; 423: 105-11. Liang S, Zhao T, Hu H, Shi Y, Xu Q, Miller MR, Duan J, Sun Z. Repeat dose exposure of PM2.5 triggers the dissemina- ted intravascular coagulation (DIC) in SD rats. Sci Total Environ. 2019; 663: 245-53. Liu C, Zhou MS, Li Y, Wang A, Chadipiralla K, Tian R, Raij L. Oral nicotine aggravates endothelial dysfunction and vas- cular inflammation in diet-induced obese rats: Role of macrophage TNFα. PLoS One. 2017; 12: e0188439. Liu Y, Cole V, Lawandy I, Ehsan A, Sellke FW, Feng J. Decreased coronary arteriolar response to KCa channel opener after cardioplegic arrest in diabetic patients. Mol Cell Biochem. 2018; 445: 187-94. Lobato NS, Filgueira FP, Akamine EH, Davel AP, Rossoni LV, Tostes RC, Carvalho MH, Fortes ZB. Obesity induced by neonatal treatment with monosodium glutamate impairs microvascular reactivity in adult rats: Role of NO and prostanoids. Nutr Metab Cardiovasc Dis. 2011; 21: 808-16. Lynn WA, Golenbock DT. Lipopolysaccharide antagonists. Immunol Today. 1992; 13: 271-76. Malakul W, Pengnet S, Kumchoom C, Tunsophon S. Naringin ameliorates endothelial dysfunction in fructose-fed rats. Exp Ther Med. 2018; 15: 3140-46. Moretti R, Caruso P. The controversial role of homocysteine in neurology: From labs to clinical practice. Int J Mol Sci. 2019; 20: 231. Nacci C, Tarquinio M, De Benedictis L, Mauro A, Zigrino A, Carratù MR, Quon MJ, Montagnani M. Endothelial dysfunction in mice with streptozotocin-induced type 1 diabetes is opposed by compensatory overexpression of cyclooxygenase-2 in the vasculature. Endocrinology 2009; 150: 849-61. Niaz K, Zaplatic E, Spoor J. Extensive use of monosodium glutamate: A threat to public health? EXCLI J. 2018; 17: 273- 78. Niazi ZR, Najmanová I, Kamagaté M, Said A, Chabert P, Auger C, Die-Kakou H, Schini-Kerth V. Preventive beneficial effect of an aqueous extract of Phyllanthus amarus Schum. and Thonn. (Euphorbiaceae) on DOCA-salt– induced hypertension, cardiac hypertrophy and dysfunc- tion, and endothelial dysfunction in rats. J Cardiovasc Pharmacol. 2020; 75: 573-83. Nie Q, Zhu L, Zhang L, Leng B, Wang H. Astragaloside IV protects against hyperglycemia-induced vascular endo- thelial dysfunction by inhibiting oxidative stress and calpain-1 activation. Life Sci. 2019; 232: 116662. Oelze M, Knorr M, Schuhmacher S, Heeren T, Otto C, Schulz E, Reifenberg K, Wenzel P, Münzel T, Daiber A. Vascular dysfunction in streptozotocin-induced experimental diabe- tes strictly depends on insulin deficiency. J Vasc Res. 2011; 48: 275-84. Olatunji LA, Seok YM, Igunnu A, Kang SH, Kim IK. Com- bined oral contraceptive-induced hypertension is accompa- nied by endothelial dysfunction and upregulated intra- renal angiotensin II type 1 receptor gene expression. Naunyn Schmiedebergs Arch Pharmacol. 2016; 389: 1147- 57. Olukman M, Can C, Erol A, Oktem G, Oral O, Cinar MG. Reversal of doxorubicin-induced vascular dysfunction by resveratrol in rat thoracic aorta: Is there a possible role of nitric oxide synthase inhibition? Anadolu Kardiyol Derg. 2009; 9: 260-66. Oyabambi AO, Areola ED, Olatunji LA, Soladoye AO. Uric acid is a key player in salt-induced endothelial dysfunc- tion: The therapeutic role of Stigma maydis (corn silk) extract. Appl Physiol Nutr Metab. 2020; 45: 67-71. Pal PB, Sonowal H, Shukla K, Srivastava SK, Ramana KV. Aldose reductase regulates hyperglycemia-induced HUVEC death via SIRT1/AMPK-α1/mTOR pathway. J Mol Endocrinol. 2019; 63: 11-25. Pieper GM, Langenstroer P, Siebeneich W. Diabetic-induced endothelial dysfunction in rat aorta: Role of hydroxyl radicals. Cardiovasc Res. 1997; 34: 145-56. Qimuge A, Liu S, Wang H, Hu M, Song L. MAPK/AP-1 pathway activation mediates AT1R up-regulation and vas- cular endothelial cells dysfunction under PM2.5 exposures. Ecotoxicol Environ Saf. 2019; 170: 188-94. Qin W, Zhang L, Li Z, Xiao D, Zhang Y, Zhang H, Mokembo JN, Monayo SM, Jha NK, Kopylov P, Shchekochikhin D, Zhang Y. Endothelial to mesenchymal transition contribu- tes to nicotine-induced atherosclerosis. Theranostics 2020; 10: 5276-89. Radovits T, Arif R, Bömicke T, Korkmaz S, Barnucz E, Karck M, Merkely B, Szabó G. Vascular dysfunction induced by hypochlorite is improved by the selective phosphodiester- ase-5-inhibitor vardenafil. Eur J Pharmacol. 2013; 710: 110- 19. Rameshrad M, Imenshahidi M, Razavi BM, Iranshahi M, Hosseinzadeh H. Bisphenol A vascular toxicity: Protective effect of Vitis vinifera (grape) seed extract and resveratrol. Phytother Res. 2018; 32: 2396-407. Ren H, Mu J, Ma J, Gong J, Li J, Wang J, Gao T, Zhu P, Zheng S, Xie J, Yuan B. Selenium inhibits homocysteine-induced endothelial dysfunction and apoptosis via activation of AKT. Cell Physiol Biochem. 2016; 38: 871-82. Reventun P, Sanchez-Esteban S, Cook A, Cuadrado I, Roza C, Moreno-Gomez-Toledano R, Muñoz C, Zaragoza C, Bosch RJ, Saura M. Bisphenol A induces coronary endothelial cell necroptosis by activating RIP3/CamKII dependent path- way. Sci Rep. 2020; 10: 4190. Ross EJ, Linch DC. Cushing's syndrome--killing disease: Discriminatory value of signs and symptoms aiding early diagnosis. Lancet 1982; 2: 646-69. Sahara M, Sata M, Morita T, Hirata Y, Nagai R. Nicorandil attenuates monocrotaline-induced vascular endothelial damage and pulmonary arterial hypertension. PLoS One. 2012; 7: e33367. Said MA. Vitamin D attenuates endothelial dysfunction in 82 Bangladesh J Pharmacol 2021; 16: 65-83 Author Info Mandeep Kumar Arora (Principal contact) e-mail: mmmarora2@gmail.com streptozotocin induced diabetic rats by reducing oxidative stress. Arch Physiol Biochem. 2020; 1: 1-5. Sandoo A, van Zanten JJ, Metsios GS, Carroll D, Kitas GD. The endothelium and its role in regulating vascular tone. Open Cardiovasc Med J. 2010; 4: 302-12. Saura M, Marquez S, Reventun P, Olea-Herrero N, Arenas MI, Moreno-Gómez-Toledano R, Gómez-Parrizas M, Muñóz-Moreno C, González-Santander M, Zaragoza C, Bosch RJ. Oral administration of bisphenol A induces high blood pressure through angiotensin II/CaMKII-dependent uncoupling of eNOS. FASEB J. 2014; 28: 4719-28. Schafer SC, Wallerath T, Closs EI, Schmidt C, Schwarz PM, Forstermann U, Lehr HA. Dexamethasone suppresses eNOS and CAT-1 and induces oxidative stress in mouse resistance arterioles. Am J Physiol Heart Circ Physiol. 2005; 288: H436-44. Schenk J, McNeill JH. The pathogenesis of DOCA-salt hyper- tension. J Pharmacol Toxicol Methods. 1992; 27: 161-70. Shawky NM, Shehatou GS, Abdel Rahim M, Suddek GM, Gameil NM. Levocetirizine ameliorates high fructose diet- induced insulin resistance, vascular dysfunction and hepa- tic steatosis in rats. Eur J Pharmacol. 2014; 740: 353-63. Si LY, Kamisah Y, Ramalingam A, Lim YC, Budin SB, Zainalabidin S. Roselle supplementation prevents nicotine- induced vascular endothelial dysfunction and remodelling in rats. Appl Physiol Nutr Metab. 2017; 42: 765-72. Steven S, Oelze M, Brandt M, Ullmann E, Kröller-Schön S, Heeren T, Tran LP, Daub S, Dib M, Stalleicken D, Wenzel P, Münzel T, Daiber A. Pentaerythritol tetranitrate in vivo treatment improves oxidative stress and vascular dysfunc- tion by suppression of endothelin-1 signaling in monocro- taline-induced pulmonary hypertension. Oxid Med Cell Longev. 2017; 2017: 4353462. Taddei S, Virdis A, Ghiadoni L, Sudano I, Salvetti A. Endo- thelial dysfunction in hypertension. J Cardiovasc Pharm. 2001; 38: S11-14. Taneja G, Mahadevan N, Balakumar P. Fish oil blunted nicotine-induced vascular endothelial abnormalities possi- bly via activation of PPARγ-eNOS-NO signals. Cardiovasc Toxicol. 2013; 13: 110-22. Tian R, Ding Y, Peng YY, Lu N. Myeloperoxidase amplified high glucose-induced endothelial dysfunction in vascular- ture: Role of NADPH oxidase and hypochlorous acid. Biochem Biophys Res Commun. 2017; 484: 572-78. Ueno Y, Mohara O, Brosnihan KB, Ferrario CM. Characteris- tics of hormonal and neurogenie mechanisms of DOC- induced hypertension. Hypertension 1988; 11: 172-77. Wang X, Chen L, Wang T, Jiang X, Zhang H, Li P, Lv B, Gao X. Ginsenoside Rg3 antagonizes adriamycin-induced cardiotoxicity by improving endothelial dysfunction from oxidative stress via up-regulating the Nrf2-ARE pathway through the activation of AKT. Phytomedicine 2015; 22: 875 -84. Wang XJ, Tian DC, Wang FW, Zhang MH, Fan CD, Chen W, Wang MH, Fu XY, Ma JK. Astaxanthin inhibits homo- cysteine induced endothelial cell dysfunction via the regu- lation of the reactive oxygen species-dependent VEGF VEGFR2 FAK signaling pathway. Mol Med Rep. 2019; 19: 4753-60. Wassmann S, Bäumer AT, Strehlow K, Van Eickels M, Grohé C, Ahlbory K, Rösen R, Böhm M, Nickenig G. Endothelial dysfunction and oxidative stress during estrogen defici- ency in spontaneously hypertensive rats. Circulation 2001; 103: 435-41. Wu H, Wu J, Zhou S, Huang W, Li Y, Zhang H, Wang J, Jia Y. SRT2104 attenuates diabetes-induced aortic endothelial dysfunction via inhibition of P53. J Endocrinol. 2018; 237: 1- 14. Yang S, Zhang L. Glucocorticoids and vascular reactivity. Curr Vasc Pharmacol. 2004; 2: 1-12. Yang XY, Qiang GF, Zhang L, Zhu XM, Wang SB, Sun L, Yang HG, Du GH. Salvianolic acid A protects against vascular endothelial dysfunction in high-fat diet fed and streptozotocin-induced diabetic rats. J Asian Nat Prod Res. 2011; 13: 884-94. Yin Y, Qi F, Song Z, Zhang B, Teng J. Ferulic acid combined with astragaloside IV protects against vascular endothelial dysfunction in diabetic rats. Biosci Trends. 2014; 8: 217-26. Zhai X, Ren D, Luo Y, Hu Y, Yang X. Chemical characteristics of an Ilex Kuding tea polysaccharide and its protective effects against high fructose-induced liver injury and vascular endothelial dysfunction in mice. Food Funct. 2017; 8: 2536-47. Zhang Y, Chen Y, Zhang Y, Li PL, Li X. Contribution of cathepsin B-dependent Nlrp3 inflammasome activation to nicotine-induced endothelial barrier dysfunction. Eur J Pharmacol. 2019; 865: 172795. Zhao YX, Tong L, Zhang GM, Zhao XH, Sa YP, Liu Y, Lu DX, Ga Q, Wu P. L-Arginine supplementation improves vascular endothelial dysfunction induced by high-fat diet in rats exposed to hypoxia. Wilderness Environ Med. 2020; 31: 400-06. Zhu J, Wang CG, Xu YG. Lycopene attenuates endothelial dysfunction in streptozotocin-induced diabetic rats by reducing oxidative stress. Pharm Biol. 2011; 49: 1144-49. Bangladesh J Pharmacol 2021; 16: 65-83 83