International Journal of Veterinary Research

en Acute exposure to environmentally relevant concentrations of phenytoin induces oxidative stress and organ-specific histopathological damage in adult zebrafish (Danio rerio) عمومى General پژوهشي Research <span style="font-size:12pt"><span new="" roman="" style="font-family:" times="">Phenytoin (PHEN), a widely prescribed antiepileptic drug, is increasingly detected in surface waters, yet its toxic effects on fish remain poorly characterized. This study evaluated the acute impact of environmentally relevant PHEN concentrations on adult zebrafish (Danio rerio). Fish (223 ± 40 mg; 3.4 ± 0.3 cm) were exposed for 96 h to 25 ng/L, 282 ng/L, and 1500 ng/L PHEN, alongside a control. PHEN exposure significantly increased lipid peroxidation (malondialdehyde, MDA), inhibited key antioxidant enzymes—catalase (CAT) and superoxide dismutase (SOD)—and elevated glutathione (GSH) levels in gut tissue (p < 0.05). Histopathological analyses revealed dose-dependent lesions, including hyperemia, branchitis, and lamellar degeneration in the gills; hyperemia and hepatic steatosis in the liver; and hyperemia, hemorrhage, and epithelial necrosis in the kidneys. Overall, short-term PHEN exposure impaired antioxidant defenses and induced oxidative and structural damage across multiple organs in a concentration-dependent manner, indicating potential ecological risks associated with pharmaceutical contamination in aquatic environments.</span></span> Phenytoin, Antiepileptic drug, Oxidative stress, Histopathology, Zebrafish 1 15 http://injvr.com/browse.php?a_code=A-10-77-1&slc_lang=en&sid=1 S. Semnani sa.semnani@gmail.com 10031947532846001556 10031947532846001556 No Department of Veterinary Hygine, SR.C., Islamic Azad University, Tehran, Iran. R. Kazempoor rkbs_kh@yahoo.com 10031947532846001557 10031947532846001557 Yes Department of Aquatic Animal Health and disease, SR.C., Islamic Azad University, Tehran, Iran. A. Chitgar Dr.ali.chitgar@gmail.com 10031947532846001558 10031947532846001558 No Assistant professor of Pathology, central organization Tehran branch, Islamic azad university,Tehran,Iran. S.S. Alavinejad Shivaalavinejad@yahoo.com 10031947532846001559 10031947532846001559 No Department of Aquatic Animal Health, Faculty of Veterinary Medicine, University of Tehran, Tehran, Iran.