Protective effects of niacin against methylmercury-induced genotoxicity and alterations in antioxidant status in rats

This study investigates the potential beneficial effects of niacin (NA; vitamin B-3) supplementation in rats chronically exposed to methylmercury (MeHg). Animals were randomly assigned to one of 4 groups (n = 6): Group I, control, received distilled water by gavage; Group II, received MeHg (100 mu g/kg/d) by gavage; Group III, received NA (50 mg/kg/d) in drinking water; Group IV, received MeHg (100 mu g/kg/d) by gavage + NA (50 mg/kg/d) in drinking water. Biochemical parameters levels of glucose, triglycerides, total cholesterol and fractions, and enzyme activities aspartate transaminase (AST) and alanine transaminase (ALT) were determined. Further, oxidative stress markers activity of glutathione peroxidase (GPx) and catalase (CAT) activity, as well as levels of reduced glutathione (GSH), malondialdehyde (MDA), and nitric oxide, were examined, and the comet assay was performed, using blood/plasma. Hg levels were measured in blood, brain, and kidneys of animals. Our results demonstrated that NA reduced adverse effects produced by MeHg. The mechanism underlying these effects appears to be related to the intrinsic antioxidant potential of NA. Considering the beneficial effects attributed to NA following MeHg exposure and that fish are the main source of both NA and MeHg, future studies need to evaluate the potential counteractive effect of NA against the adverse consequences of MeHg exposure in fish-eating populations.