Effects of methylparaben on the activities of leukocyte-derived enzymes and antioxidant defense system of African catfish, Clarias gariepinus.

Methylparaben (MeP) has a wide application in several industries including cosmetics, pharmaceuticals, and personal care products (PCP), thus accounting for its ubiquity in the environment. The aim of this study was to investigate the effects of exposure to sub-lethal concentrations of MeP on cytotoxicity, immunotoxicity, and antioxidant defense mechanisms utilizing juvenile African catfish, Clarias gariepinus as a model. Juvenile C. gariepinus were exposed to 0.74 or 1.48 mg/L MeP for 28 days after which the liver was excised for determination of cytotoxicity and oxidative stress parameters. The head kidney was extracted for histopathological analysis. Control fish were maintained in water spiked with 10 μL/L ethanol. The levels of respiratory burst, lipid peroxidation, and activities of superoxide dismutase and lactate dehydrogenase increased significantly in MeP-exposed fish especially at 1.48 mg/L compared to control. The % of DNA fragmentation also significantly increased across the treatments. Exposure to MeP resulted in various histological lesions including vacuolation of epithelial cells, infiltration of renal tubules with inflammatory cells, and thickening of the glomerular membrane in the head kidney. Data demonstrated that MeP exerted various adverse effects including cytotoxicity, immunotoxicity, and oxidative stress in the fish, C. gariepinus, attributed to possible activation of cellular stress inflammatory pathways.