The University of Toledo Translation Journal of Medical Sciences 
Internal Medicine Abstract, Department of Medicine Research Symposium UTJMS 2023 May 5; 11(1):e1-e2 

Antioxidant Therapy Restores Hepatic Metabolic Enzymes 
Altered by Exposure to Microcystin-LR in a Murine 
Model of Non-Alcoholic Fatty Liver Disease 

Jonathan Hunyadi, BS1*, Apurva Lad, PhD1, Joshua D. Breidenbach, MS1, Jacob 
Connolly, UG1, Fatimah K. Khalaf, MBchB, PhD1, Prabhatchandra Dube, PhD1, 
Shungang Zhang, PhD1, Andrew L. Kleinhenz, BS1, David Baliu-Rodriguez, PhD1, 
Dragan Isailovic, PhD1, Terry Hinds, PhD, Deepak Malhotra MD, PhD2, Steven T. 
Haller PhD1, David J. Kennedy PhD1

1Division of Cardiovascular Medicine, Department of Medicine, The University of 
Toledo, Toledo, OH 43614 
2Division of Nephrology, Department of Medicine, The University of Toledo, 
Toledo, OH 43614 

*Corresponding author: Jonathan.hunyadi@rockets.utoledo.edu

Published: 05 May 2023 

Introduction: We have shown that exposure to the environmental liver toxin Microcystin-LR (MC-LR) 
in the setting of pre-existing Non-alcoholic Fatty Liver Disease (NAFLD) induces significant 
hepatotoxicity and oxidative stress. Therefore, we hypothesized if targeted antioxidant therapy would 
improve MC-LR metabolism and reduce hepatic injury. 

Methods: Six-week-old C57Bl/6J mice fed with choline-deficient high fat diet with 0.1% methionine to 
induce NAFLD were gavaged with 100 µg/kg MC-LR/24 hrs for 15 days. Antioxidants included 
augmentation of the glutathione detoxification pathway with N-acetylcysteine (NAC) given at 40 mM in 
drinking water; and interruption of specific Src kinase-mediated oxidant signaling pathways with a novel 
peptide (pNaKtide) at 25 mg/kg injected intraperitonially once a week. 

Results: Histologic analysis revealed significant increase in hepatic inflammation with MC-LR 
exposure which was attenuated in both antioxidant treatment groups. 8-OHDG levels in urine and 
protein carbonylation in liver, both markers of oxidative stress, were significantly downregulated upon 
antioxidant treatment after MC-LR exposure. Analysis of key drug transporters as well as Phase I & II 
enzymes using quantitative PCR revealed that exposure to MC-LR significantly upregulated expression 
of the drug transporter Abcb1a; Cyp3a11, Phase I enzyme belonging to the Cytochrome P450 family 
whereas Phase II enzymes, Pkm (Pyruvate kinase, muscle), Pklr (Pyruvate kinase, liver, and RBC) and 
Gad1 (Glutamic acid decarboxylase) were significantly downregulated. Antioxidant therapy with both 
pNaKtide and NAC significantly attenuated these changes and restored microcystin detoxification.   

https://dx.doi.org/10.46570/utjms.vol11-2023-697 

https://dx.doi.org/10.46570/utjms.vol11-2023-697
mailto:Jonathan.hunyadi@rockets.utoledo.edu


https://dx.doi.org/10.46570/utjms.vol11-2023-697 UTJMS 11(1):e1-e2 

https://dx.doi.org/10.46570/utjms.vol11-2023-697 2 ©2023 UTJMS 

Conclusion: These results suggest that NAFLD significantly alters the metabolism of MC-LR, and this 
can be reversed with targeted antioxidant treatment. 

https://dx.doi.org/10.46570/utjms.vol11-2023-697
https://dx.doi.org/10.46570/utjms.vol11-2023-697