Bangladesh Journal of Pharmacology Meta-Analysis Efficacy of herbal medicines and standard antidepressants on neurotransmitter and behavioral outcomes in animal models of depression BJP Introduction Depression is a prevalent and debilitating psychiatric disorder characterized by low mood, loss of interest (anhedonia), cognitive dysfunction, and behavioral dis- turbances. Individuals with depression often struggle with daily activities, experiencing reduced productivity and diminished quality of life due to persistent sadness and lack of motivation (Almaghrabi et al., 2023). The global burden of depression estimating that approxi- mately 280 million people worldwide are affected (World Health Organization, 2023). Moreover, depre- ssion is ranked as the second major cause of years lived with disability and is a major contributor to suicide- related death and physical health complications (Yan et al., 2024). Given these severe implications, enhancing treatment strategies for depression remains a critical research priority (Kupferberg and Hasler, 2023). The pharmacological management of depression prima- rily targets neurotransmitter imbalances, with selective serotonin reuptake inhibitors (SSRIs) and monoamine oxidase-A inhibitors (MAOIs) being the most prescrib- ed classes of antidepressants. However, long-term ad- ministration of these drugs faces treatment challenges such as reduced receptor sensitivity and higher therapy costs (Chen et al., 2024). While these medications can be effective, they are often associated with significant limitations, including reduced long-term efficacy due to receptor desensitization and adaptive neuroplasticity changes, adverse side effects such as gastrointestinal distress, sexual dysfunction, and weight gain that impact treatment adherence, and withdrawal symp- toms upon discontinuation. Furthermore, treatment Abstract Herbal-based therapies show potential as antidepressants, though compara- tive efficacy remains uncertain. This study employed a meta-analysis to evaluate the efficacy of herbal interventions against standard antidepressants in animal depression models. A systematic search of PubMed, ScienceDirect, Cochrane, and Google Scholar (up to January 2025) identified 20 eligible studies. The behavior (open field test, tail suspension test) and neurotrans- mitters (serotonin, dopamine, noradrenaline) were analyzed as outcomes. Random-effects models were used, and risk of bias was assessed via SYRCLE. Curcumin improved open field test scores and increased serotonin and noradrenaline levels. Rosemary essential oil showed the strongest effect in the tail suspension test. Anthocyanins enhanced dopamine levels while zinc oxide nanoparticles exhibited effects comparable to curcumin. This finding supports the antidepressant potential of specific herbal, particularly curcu- min, rosemary essential oil, and anthocyanins. Further standard research is necessary to confirm clinical relevance. Article Info Received: 13 April 2025 Accepted: 13 May 2025 Available Online: 23 May 2025 DOI: 10.3329/bjp.v20i2.81017 Cite this article: Kurnianingsih N, Puling IMDR, Ca- hayani WA. Efficacy of herbal medi- cines and standard antidepressants on neurotransmitter and behavioral out- comes in animal models of depres- sion. Bangladesh J Pharmacol. 2025; 20: 51-61. Efficacy of herbal medicines and standard antidepressants on neuro- transmitter and behavioral outcomes in animal models of depression Nia Kurnianingsih1, Imke Maria Del Rosario Puling2, and Wike Astrid Cahayani3 1Department of Physiology, Faculty of Medicine, Universitas Brawijaya, Malang, East Java, 65145, Indonesia; 2Medical Doctor Profession Program, Faculty of Medicine, Universitas Brawijaya, Malang, East Java, 65145, Indonesia; 3Department of Anatomy-Histology, Faculty of Medicine, Universitas Brawijaya, Malang, East Java, 65145, Indonesia. This work is licensed under a Creative Commons Attribution 4.0 License. You are free to copy, distribute and perform the work. You must attribute the work in the manner specified by the author or licensor. A Journal of the Bangladesh Pharmacological Society (BDPS) Bangladesh J Pharmacol 2025; 20: 51-61 Journal homepage: www.banglajol.info Abstracted/indexed in Academic Search Complete, Agroforestry Abstracts, 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 M e ta -a n a ly s is resistance affects up to 30% of patients, substantially limiting therapeutic options for many individuals (Kolasa and Faron-Gorecka, 2023). Depression is increasingly recognized as a multifactor- rial disorder, involving not only monoaminergic dys- function but also neuroinflammation, oxidative stress, hypothalamic-pituitary-adrenal axis dysregulation, and neuronal remodelling (Cui et al., 2024). These complex neurobiological underpinnings highlight the urgent need for alternative and complementary therapeutic approaches that target multiple pathophysiological mechanisms Growing evidence suggests that herbal-based interven- tions may offer antidepressant effects through multi- modal mechanisms, including neurotransmitter modu- lation, anti-inflammatory and antioxidant properties, and enhancement of neurogenesis and synaptic plasti- city. Several herbal compounds have been extensively investigated for their antidepressant potential in pre- clinical studies. Curcumin, a bioactive compound from turmeric, has been shown to enhance neurotrophic factors, regulate hypothalamic-pituitary-adrenal axis activity, and improve neurotransmitter balance (Zhang et al., 2020). Anthocyanins, found in purple sweet potatoes and berries, have been shown to modulate dopamine-related and gamma-aminobutyric acid-rela- ted neurotransmission, suggesting potential mood- stabilizing effects (Kurnianingsih et al., 2024). Tea polyphenols, particularly L-theanine and catechins from green tea extracts, exhibit neuroprotective and anxiolytic properties (Rothenberg and Zhang, 2019). Additionally, Aegle marmelos has been reported to modulate monoamine neurotransmitters, showing potential antidepressant effects in animal models (Poja- la and Sayeli, 2023). Despite the promising potential of herbal interventions, the existing literature presents methodological inconsis- tencies and variable efficacy results. For instance, curcumin's antidepressant effects vary across studies, influenced by dosage, administration route, and bio- availability challenges (Ramaholimihaso et al., 2020). Anthocyanins demonstrate significant antidepressant- like effects in some models, but their efficacy is inconsistent in others, potentially due to differences in experimental design and pharmacokinetics (Zaa et al., 2023). Many studies assess individual herbal treatments in isolation, comparing them only to placebo or stan- dard medications without direct comparisons between different herbal interventions. These methodological disparities limit our understanding of which herbal compounds offer the most robust antidepressant effects. Furthermore, using various animal models, behavioral paradigms, and neurochemical assays complicates direct comparisons between studies. The limitations of conventional antidepressants, cou- pled with the promising but fragmented evidence for herbal interventions, underscore the pressing need for a comprehensive evaluation of alternative treatment stra- tegies. The high prevalence of treatment-resistant depression and medication side effects creates an ur- gent clinical imperative to identify effective comple- mentary approaches. Given the methodological varia- tions across existing studies, a systematic and quantita- tive approach that enables direct and indirect compari- sons across multiple interventions would provide a more comprehensive and unbiased evaluation of their relative efficacy. Therefore, this study aimed to systematically evaluate and compare the antidepressant efficacy of various herbal interventions using a network meta-analysis approach. Specifically, it seeks to assess behavioral outcomes (open field test, tail suspension test) to determine antidepressant-like effects, analyze neuro- transmitter levels (serotonin, dopamine, noradrenaline) to elucidate potential mechanisms of action, and com- pare the efficacy of herbal interventions against stan- dard antidepressants to explore their clinical relevance. By synthesizing preclinical evidence and accounting for methodological variations across studies, this meta- analysis provides a more comprehensive and balanced understanding of herbal treatments in depression management. Materials and Methods The study was performed by using the Preferred Repor- ting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement guidelines (Page et al., 2021). The study protocol was registered in PROSPERO (registra- tion number: CRD420251016020), ensuring the method- logical transparency and reproducibility. Search strategy A comprehensive search of four major scientific data- bases- PubMed, ScienceDirect, Cochrane, and Google Scholar- was conducted up to January 2025 to identify relevant studies on the efficacy of herbal interventions in animal models of depression. The search strategy incorporated Boolean operators (AND, OR) to maxi- mize the retrieval of relevant literature. The literature search was structured around three core domains: 1) depression models in animals, 2) herbal and standard antidepressant interventions, and 3) behavioral and neurotransmitter outcomes. The specific search strings used in each database are detailed in Table I. Study eligibility criteria The study eligibility criteria were determined to ensure the homogeneity of the studies. The inclusion in this study were as follows: 1) studies that involve depre- ssion model animals as their sample, 2) studies comparing outcomes between various herbal and 52 Bangladesh J Pharmacol 2025; 20: 51-61 medication interventions regarding depression, and 3) studies involving at least one of these parameters, namely open field test, tail suspension test, serotonin level, dopamine level, and noradrenaline level. On the contrary, the criteria for exclusion in this study were 1) human sampling, 2) irretrievable articles, 3) articles with incompatible language, and 4) non-peer-reviewed articles. The researchers individually assessed each study to decide if it met the criteria, after which they deliberated on any disagreements until reaching a consensus. Outcome measures This paper examined five outcome parameters to assess the efficacy of herbal and medication interventions in animal model of depression. The analysis included efficacy parameters such as the open field test, tail suspension test, and levels of serotonin, dopamine, and noradrenaline. Differences in interpretation were resolved through discussion. Quality assessment Two reviewers used the critical appraisal tool to independently determine whether each study has a low, moderate, or high risk of bias using the Systematic Review Centre for Laboratory Animal Experimentation (SYRCLE) risk of bias tool for animal studies (Hooijmans et al., 2014). The SYRCLE has ten domains of study quality, which were analyzed and summed up for the overall results. Subsequently, the assessment result for SYRCLE was extracted into a Microsoft Excel 2021 spreadsheet and then uploaded to the ROBVIS website to be visually presented using the traffic light system (McGuinness and Higgins, 2021) Statistical analysis RStudio was used for the network meta-analysis because all studies mentioned variable interventions and outcomes. Network meta-analysis was chosen to compare the direct and indirect effects of these strategies with placebo as the control group using the package “netmeta” in RStudio 2020 (RStudio Team 2020). The network graph was generated using the "netgraph" function, visually connecting and comparing all intervention strategies with the control group. Statistical estimation was performed using a 95% confidence interval (CI) to assess continuous data. Random effect models were used due to the heterogeneity of the interventions included. Using cutoff criteria of 0%, 25%, 50%, and 75% to indicate insignificant, low, moderate, and high levels of heterogeneity, respectively, I2 statistics were used to assess heterogeneity. Closed loops were formed and verified to ensure the consistency of the network. Forest plots were utilized to summarize the pooled strategy comparisons for all outcome measures, with the control group as the reference. Results Study selection and identification A total of 22 studies underwent a comprehensive eva- luation after eliminating the duplicate studies. Ulti- mately, 20 studies were chosen for inclusion in the meta Table I Literature search terms for included studies Database Keywords PubMed #1 “depression” [MeSH Terms] #2 ((“depression” [Title/Abstract]) OR (“depressive behaviour" [Title/Abstract])) #3 #1 OR #2 #4 ((“herbal" [Title/Abstract]) OR ("curcumin" [Title/Abstract]) OR ("anthocyanin" [Title/Abstract]) OR ("medication" [Title/Abstract]) OR ("antidepressant treatment" [Title/Abstract])) #5 #3 OR #4 #6 ((“outcome" [Title/Abstract]) OR ("serotonin" [Title/Abstract]) OR ("dopamine" [Title/Abstract]) OR ("medication" [Title/Abstract]) OR ("noradrenaline" [Title/Abstract]) OR ("open field test" [Title/ Abstract]) OR ("tail suspension test" [Title/Abstract])) #7 #6 AND #5 #8 #7, Filter : Trial ScienceDirect (“Rodent” OR “Rabbit OR "Animal model" OR "Experimental animal") AND (“Herbal” OR “Curcumin” OR “Anthocyanin” OR "Herbal substances" OR “Medication” OR "Antidepressant treatment") AND (“Serotonin” OR “Dopamine” OR “Noradrenaline” OR “Neurotransmitters” OR "Open field test" OR "Tail suspension test") Cochrane (“Rodent” OR “Rabbit OR "Animal model" OR "Experimental animal") AND (“Herbal” OR “Curcumin” OR “Anthocyanin” OR "Herbal substances" OR “Medication” OR "Antidepressant treatment") AND (“Serotonin” OR “Dopamine” OR “Noradrenaline” OR “Neurotransmitters” OR "Open field test" OR "Tail suspension test") Google Scholar (rodent animal AND (depression OR depressive)) AND (SSRI OR SNRI OR antidepressant OR herbal OR plant) AND (behavioral outcome OR neurotransmitter) Bangladesh J Pharmacol 2025; 20: 51-61 53 -analysis (Amoateng et al. 2015; Arora et al. 2011; Bhatt et al. 2022; Chang et al. 2016; Chi et al. 2022; Dudau et al. 2023; Fahmy et al. 2024; Gazal et al. 2014; Kurnianingsih et al., 2024; Madiha and Haider, 2019; Moorkoth et al., 2021; Pan et al., 2021; Sartim et al., 2021; Sasaki et al., 2021, 2022a, 2022b; Sharma et al., 2022; Zhai et al., 2024; Zhao et al., 2014), as depicted in Figure 1. The original database search resulted in 1,080 studies from eight databases searched, namely PubMed, ScienceDirect, Cochrane, and Google Scholar. Through title and abstract screening, 955 articles were removed, and 125 were screened for duplication. Dupli- cate screening resulted in 102 removed articles. Twenty- two were further assessed for eligibility, and two articles were removed due to unrelated or insufficient data. The final step resulted in 20 animal experimental studies included in the qualitative synthesis. Characteristics of the included studies Each study's demography and clinical characteristics were examined and listed in Supplementary Table I. Risk of bias assessment of the included studies Twenty studies were assessed using the SYRCLE. The overall assessment of all studies shows that 16 included studies were of low risk of bias, however, 4 studies showed moderate risk of bias. The overall risk of bias, as shown in the summary plot, is reported to be about 80% low risk, which indicates that most of the included studies were objected to good quality (Figure 2). Behaviors Open field test Seven studies reported open field test results were analyzed through network meta-analysis. The graph plot in Figure 3A shows a direct comparison/relation- ship between all herbal and medication results regar- ding depression. The nodes denote the number of studies included in each arm of treatment. Curcumin has the second biggest node, next to placebo, indicating it has the second highest number of animals (24). Followed by medication, including reserpine, fluoxe- tine, imipramine, and bupropion (18), ethanol extract from Gynura procumbens stems (EEGS) (15), hydro- ethanolic extract of Aegle marmelos (EAM) (6), and lastly anthocyanin (5). Numbers in the line between each node indicate the number of studies comparing each intervention. Forest plot of network meta-analysis using a random effect model of the plot. Figure 3B shows a significant result with high heterogeneity (p=0.0001; I2=82.4%) favoring EAM with mean difference (MD) of -8.35 [95% CI: -9.92 — -6.78] com- pared to placebo, followed by curcumin -3.50 [95% CI: - 5.94 — -1.06], medication -3.41 [95% CI: -6.14 — -0.69], EEGS -2.09 [95% CI: -7.43 — 3.25], and anthocyanin - Figure 1: Preferred reporting items for systematic reviews and meta-analyses (PRISMA) flowchart for study identification and selection Articles identified through databases searching (n = 1080) Articles screened (n = 125) Articles after duplicate removed (n = 23) Full-text articles assessed for eligibility (n = 22) Studies included in synthesis (n = 20) Articles excluded based on title and abstract (n = 955) Duplicate articles removed (n = 102) Data unrelated to the focus of the review (n = 1) Insufficient detail for adequate evaluation (n = 1) 54 Bangladesh J Pharmacol 2025; 20: 51-61 1.93 [95% CI: -5.52 — 1.66]. Tail suspension test Nine studies reported that tail suspension test results were analyzed using network meta-analysis. In Figure 3C, the graph plot depicts the direct comparisons and relationships between various herbal and medication- based interventions for the tail suspension test as depressive-like behavior. The node sizes correspond to the number of studies in each treatment arm, with medication having the second-largest node (32 animals), following placebo (47 animals). Other inter- ventions include EEGS (15 animals), microalgae (14 animals), rosemary essential oil (7 animals), Synedrella nodiflora (SNE) (7 animals), Cochlospermum religiosum (CSR) leaf (6 animals), and curcumin (6 animals). The Figure 2: Risk of bias summary using the SYRCLE tool for animal trials. The green region represents studies with a low risk of bias, the yellow area shows studies with ‘some concerns’ risk of bias, the red area shows studies with a high risk of bias Risk of bias D1 D2 D3 D4 D5 D6 D7 D8 D9 D10 Overall Dudau et al., 2023 (2) Gazal et al., 2013 Moorkoth et al., 2021 Sartim et al., 2021 (2) Zhai et al., 2024 Sharma et al., 2022 (2) Kumianingsih et al., 2024 Bhatt et al., 2022 Amoateng et al., 2018 Sasaki et al., 2021 Sasaki et al., 2022 Pan et al., 2021 Fahmy et al., 2023 Malidha et al., 2019 Zhao et al., 2013 Chi et al., 2022 Li et al., 2023 Habeeb et al., 2022 Teksen et al., 2024 Arora et al., 2011 S tu d ie s D1: Sequence generation D2: Baseline characteristics D3: Allocation concealment D4: Random housing D5: Blinding (performance) D6: Random outcome assessment D7: Blinding (detection) D8: Incomplete outcome data D9: Selective outcome reporting D10: Other sources of bias Overall Judgement Unclear Low 0% 25% 50% 75% 100% No information Critical High Unclear Low Bangladesh J Pharmacol 2025; 20: 51-61 55 numbers on the connecting lines indicate the number of studies comparing each intervention pair. Meanwhile, the forest plot, as depicted in Figure 3D, demonstrates the results of the random effects model analysis, showing significant findings with low hetero- geneity (p=0.0001; I²=27.7%). Rosemary essential oil was favored with an MD of -107.5 [95% CI: -174.44 to - 41.56] compared to placebo, followed by microalgae (- 67.06 [95% CI: -115.53 to -18.59]), CSR leaf (-49.17 [95% CI: -122.76 to -24.42]), medication (-45.77 [95% CI: -85.17 to -6.37]), SNE (-44.57 [95% CI: -117.94 to 28.80]), curcumin (-0.19 [95% CI: -62.06 to 61.68]), and EEGS (0.00 [95% CI: -61.98 to -61.68]). Neurotransmitter Serotonin level Ten studies assessing field suspension test results were analyzed through a network meta-analysis. Figure 4A presents a graph plot illustrating the direct comparisons and relationships between different herbal and medication-based interventions for depression. The node sizes reflect the number of participants in each treatment group, with placebo having the largest node (44 animals), followed by medication (29 animals), curcumin (21 animals), and curcumin combination (21 animals). Other interventions include curcumin-conju- gated zinc oxide nanoparticle/ZnO NP (7 animals), rotenone (6 animals), and Rehmannia glutinosa decoc- tion/LBRD (6 animals). The numbers on the connecting lines represent the number of studies comparing each intervention pair. Meanwhile, the forest plot as depicted in Figure 4B, demonstrates the results of the random effects model analysis, showing significant findings with high hetero- geneity (p=0.0006; I²=76.9%). Curcumin was favored with an MD of 66.35 [95% CI: -5.15 to 137.85] compared to placebo, followed by ZnO NP (65.04 [95% CI: -51.87 to 181.94]), and medication (35.77 [95% CI: -16.64 to 88.18]), while reverse results was found in curcumin combination (-16.14 [95% CI: -73.10 to 40.82]), LBRD (- 36.00 [95% CI: -129.47 to 57.47]), and rotenone (-179.47 [95% CI: -271.96 to 86.98]). Dopamine level Ten studies evaluating dopamine levels were analyzed using network meta-analysis. Figure 4C displays a graph plot depicting the direct comparisons and relationships between various herbal and medication- based interventions for depression. The node sizes indicate the number of participants in each treatment Figure 3: Network meta-analysis graph plot (left panel) and network meta-analysis random effect model forest plot (right panel) for behavioral outcomes. Analysis for open filed test behavior from six studies (A-B). Analysis for tail suspension test behavior from nine studies (C-D) A C D B Anthocyanin Curcumin EAM EEGS Medication Placebo CSR leaf Curcumin EEGS Medication Microalgae Placebo Rosemary EO SNE Comparison: Other vs Placebo Treatment (Random effects model) MD 95%-Cl Comparison: Other vs Placebo Treatment (Random effects model) MD 95%-Cl Medication (n=18) Curcumin (n=24) EEGS (n=15) Curcumin (n=6) EEGS (n=15) Microalgae (n=14) SNE (n=7) Medication (n=32) CSR leaf (n=6) Rosemary EO (n=7) Placebo (n=47) Placebo (n=32) Anthocyanin (n=5) EAM (n=6) 56 Bangladesh J Pharmacol 2025; 20: 51-61 group, with placebo having the largest node (44 ani- mals), followed by medication (29 animals), curcumin (21 animals), curcumin combination (14 animals), ZnO NP (7 animals), anthocyanin (7 animals), LBRD (6 animals), and rotenone (6 animals). The numbers on the connecting lines represent the studies comparing each intervention pair. Figure 4D presents the forest plot from the random effects model analysis, revealing significant findings with high heterogeneity (p<0.0001; I²=99.1%). Among the interventions, anthocyanin showed a significant positive effect with a mean difference (MD) of 4.05 [95% CI: -83.49 to 91.59] compared to placebo. Meanwhile, other interventions showed a negative effect, respec- tively, from the smallest to largest, LBRD (-7.06 [95% CI: -94.64 to 80.52]), curcumin (-19.84 [95% CI: -86.81 to 47.12]), ZnO NP (-20.58 [95% CI: -130.80 to 89.64]), medication (-44.36 [95% CI: -95.01 to 6.30]), curcumin combination (-150.35 [95% CI: -217.77 to -82.94]), and rotenone (-1243.84 [95% CI: -1332.53 to -1155.15]). Noradrenaline level Five studies of noradrenaline level results were ana- lyzed through network meta-analysis. Figure 4E presents a graph plot that visualizes the direct comparisons and interactions between various herbal Figure 4: Network meta-analysis graph plot and network meta-analysis random effect model forest plot for neurotransmitter outcomes. The size of the node indicates the number of participants in each intervention. Analysis for serotonin level from eight interventions (A-B). Analysis for dopamine level from ten interventions (C-D). Analysis for noradrenaline level from five interven- tions (E-F) F D B E C A Comparison: Other vs Placebo Treatment (Random effects model) MD 95%-Cl Comparison: Other vs Placebo Treatment (Random effects model) MD 95%-Cl Comparison: Other vs Placebo Treatment (Random effects model) MD 95%-Cl Curcumin Curcumin combination LBRD Medication Placebo Rotenone ZnO NP Anthocyanin Curcumin Curcumin combination LBRD Medication Placebo Rotenone ZnO NP Curcumin Curcumin combination Medication Placebo ZnO NP Placebo (n=44) Placebo (n=44) Placebo (n=26) Medication (n=29) Medication (n=29) Medication (n=13) Curcumin (n=21) Curcumin (n=21) Curcumin (n=13) Curcumin combina- tion (n=7) Curcumin combina- tion (n=14) Curcumin combina- tion (n=21) ZnO NP (n=7) ZnO NP (n=7) ZnO NP (n=7) Rotenone (n=6) Rotenone (n=6) LBRD (n=6) LBRD (n=6) Anthocyanin (n=7) Bangladesh J Pharmacol 2025; 20: 51-61 57 and medication-based treatments for depression. The size of each node corresponds to the number of partici- pants in each treatment group, with placebo having the highest number (26 animals), followed by medication (13 animals), curcumin (13 animals), ZnO NP (7 animals), and curcumin combination (7 animals). The numbers along the connecting lines indicate the number of studies that compared each intervention pair. The forest plot in Figure 4F illustrates the results of the random effects model analysis, highlighting significant findings with high heterogeneity (p=0.0001; I²=97.8%). Curcumin demonstrated the most substantial effect, with a mean difference (MD) of 73.30 [95% CI: 24.80 to 121.80] compared to placebo. This was followed by ZnO NP (73.12 [95% CI: 7.33 to 138.91]), medication (12.45 [95% CI: -19.92 to 44.82]), while curcumin combination (-299.10 [95% CI: -351.67 to -246.53]) showed a reverse effect. Discussion This study systematically reviewed the different outcomes of behavioral test and neurotransmitter levels among various herbal interventions for depression in animal models. Through a comprehensive literature search, 20 studies using diverse herbal treatments were included. The open field and tail suspension tests were used as behavioral parameters, while serotonin, dopamine, and noradrenaline levels served as neurotransmitter outcome measures. This meta-analysis provides valuable insights into the comparative efficacy of herbal treatments, emphasizing the need for a nuanced approach to understanding their therapeutic potential in depression. The behavioral analysis through the open field test revealed that curcumin demonstrated greater efficacy than other herbal treatments in the open field test of behavior analysis. This finding aligns with a previous study that identified multiple mechanisms of action for curcumin, including enhancement of neurotrophic factors, improvement of mitochondrial activity, normalization of inflammation, reduction of oxidative stress, regulation of the hypothalamic-pituitary-adrenal axis and restoration of neurotransmitter activity (Lopresti, 2022). Notably, curcumin also exhibited the highest effectiveness in increasing serotonin levels among herbal studies. Serotonin plays a crucial role in mood regulation, and this finding strengthens existing evidence that curcumin modulates the serotonergic pathway, possibly through the inhibition of monoamine oxidase enzymes or by increasing the availability of tryptophan for serotonin synthesis (Ramaholimihaso et al., 2020). Additionally, curcumin enhanced the brain- derived neurotrophic factor in the hippocampus (Hosseinzadeh et al., 2012) In the tail suspension test, which precisely measures despair behavior in animal models of depression (Ueno et al., 2022), rosemary essential oil demonstrated the most pronounced effect in reducing immobility time. This supports its potential to alleviate depressive symptoms through anti-inflammatory properties and enhancement of neurotransmitter levels, such as serotonin and dopamine. Research has shown that rosemary essential oil significantly reduced the production of pro-inflammatory cytokines Interleukin- 1β and tumor necrosis factor-α (Niu et al., 2025). Furthermore, rosemary contains rosmarinic acid, a key component of rosemary, appears to mitigate oxidative stress by reducing reactive oxygen species, lipid peroxidation, and malondialdehyde, while concurrently enhancing the antioxidant defense mechanism through increased activities of enzymes such as superoxide dismutase, catalase, and glutathione, as well as by upregulation of nuclear factor erythroid-2 expression (Abdel-Azeem et al., 2017; Dahchour, 2022). At the neurotransmitter level, anthocyanins exerted the most pronounced effect on dopamine levels. These findings corroborated previous research indicating that anthocyanins from purple sweet potatoes modulate neurotransmitter levels, specifically dopamine and gamma-aminobutyric acid, with predicted activity on dopamine receptors and inhibition monoamine oxidase enzyme activity (Kurnianingsih et al., 2021, 2024a). Anthocyanins have been shown to reduce microglial reactivity by inhibiting the pathway of nuclear factor kappa-light-chain-enhancer of activated B cells, thereby reducing inflammatory cytokine production and free radical formation and alleviating neuronal excitotoxicity (Zaa et al., 2023). Curcumin most significantly enhanced noradrenaline levels, like its effect on serotonin, further underscoring its pivotal role in the monoaminergic neurotransmitter system. Interestingly, conjugating curcumin with zinc oxide nanoparticles demonstrated efficacy comparable to curcumin alone in elevating noradrenaline levels. This effect may be attributed to the enhanced ability of nanoparticles to cross the blood–brain barrier due to their small size and high lipid solubility, facilitating targeted delivery to the brain (Hersh et al., 2022). The current findings highlight the differential efficacy of herbal treatments for depression, reflected in the high score of heterogeneity observed across studies. Multiple factors contribute to this heterogeneity, including variations in study design, intervention protocols, dosage regimens, treatment duration, and outcome measures (Higgins et al., 2003). This study examined animal research by evaluating species diversity, experimental designs, and methodological approaches. While this heterogeneity presents challenges for direct comparison, it also offers opportunities for further exploration to identify specific 58 Bangladesh J Pharmacol 2025; 20: 51-61 therapeutic targets for depression and to assess the potential synergistic effects of combining various herbal treatments. Several limitations must be acknowledged when inter- preting these results. The high heterogeneity across stu- dies limits the generalizability of the findings and necessitates careful consideration when translating these results to clinical applications. Additionally, the lack of standardized dosing protocols and variations in animal models used across studies present challenges for direct comparison. Despite these limitations, this research significantly contributes by bridging tradi- tional herbal medicine with neuroscience, highlighting the potential effects of natural compounds on mental health. The findings of this meta-analysis have important implications for depression treatment research. The differential effects of herbal interventions on behavioral and neurotransmitter parameters suggest that persona- lized approaches might be beneficial, with specific herbal compounds targeting aspects of depression symptomatology. The promising results with curcumin, rosemary essential oil, and anthocyanins provide a foundation for more focused investigations into their mechanisms of action and potential clinical applica- tions. Moreover, the comparable efficacy of some herbal treatments to conventional antidepressants highlights their potential as complementary or alternative thera- peutic options, particularly for patients who experience adverse effects from standard medications or have treatment-resistant depression. Conclusion This meta-analysis study highlights the diverse effects of herbal treatments on depression-like behavior in animal models. Curcumin, rosemary essential oil, and anthocyanins demonstrated distinct benefits on beha- vioral and neurotransmitter outcomes. Curcumin showed greater efficacy in the open field test and significantly increased serotonin and noradrenaline levels. Rosemary essential oil exhibited the most substantial antidepressant effect in the tail suspension test, while anthocyanins specifically enhanced dopa- mine levels. Additionally, zinc oxide nanoparticles combined with curcumin showed promising effects, suggesting potential benefits in improving bioavaila- bility. The variability in efficacy across different herbal treatments underscores the complexity of their pharma- cological mechanisms and the need for further research. Future studies should focus on clinical translation, detailed mechanistic investigations, standardization of experimental protocols, and exploration of potential synergistic effects. This research provides a foundation for more targeted investigations into the antidepressant potential of herbal compounds, poten-tially leading to novel therapeutic approaches for depression. Financial Support This work was supported by the Directorate of Research and Community Service Universitas Brawijaya under grant no. 00145.26/UN10.A0501/B/PT.01.03.2/2024. The funding body had no role in the design, execution, analysis, or interpretation of the data, nor in the decision to submit the manuscript for publication. Ethical Issue Not applicable Conflict of Interest Authors declare no conflict of interest References Abdel-Azeem AS, Hegazy AM, Zeidan HM, Ibrahim KS, El- Sayed EM. Potential renoprotective effects of rosemary and thyme against gentamicin toxicity in rats. J Diet Suppl. 2017; 14: 380-94. Almaghrabi SA, Clark SR, Baumert M. Bio-acoustic features of depression: A review. Biomed Signal Process Control. 2023; 85: 105020. Amoateng P, Kukuia KKE, Mensah JA, Osei-Safo D, Adjei S, Eklemet AA, Vinyo, EA, Karikari TK. An extract of Synedrella nodiflora (L) Gaertn exhibits antidepressant pro- perties through monoaminergic mechanisms. Metab Brain Dis. 2018; 33: 1359-68. 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