Abstract

Withania somnifera (WS) an ayurvedic medicinal herb is widely known for its memory enhancing ability and improvement of brain function. In the present study, we tested the hypothesis that WS prophylaxis could offset neurotoxicant-induced oxidative dysfunctions in developing brain employing a rotenone (ROT) mouse model. Initially, we assessed the potential of WS oral supplements (100-400 mg/ kg b.w/ d, 4wks) to modulate the endogenous levels of oxidative markers in cerebellum (cb) and striatum (st) of prepubertal (PP) mice. Further, we assessed the induction of oxidative stress in cb and st of mice administered with ROT (i.p. 0.5 and 1mg/ kg b.w, 7d). ROT caused significant elevation in the levels of reactive oxygen species (ROS), malondialdehyde (MDA), hydroperoxides (HP) and nitric oxide (NO) levels in both brain regions. Further ROT caused significant perturbations in the levels of reduced glutathione (GSH), activity levels of antioxidant enzymes, acetylcholinesterase and mitochondrial dysfunctions suggesting a state of oxidative stress. In a satellite study, we examined the protective effects of WS root powder (400mg/ kg b.w/ d, 4wks) in PP mice challenged with ROT (0.5 mg/ kg b.w/ d, 7 d). WS prophylaxis significantly offset ROT-induced oxidative damage in st and cb as evident by the normalized levels of oxidative markers (MDA, ROS levels and HP) and restoration of depleted GSH levels. Further, WS effectively normalized the NO levels in both brain regions suggesting its antiinflammatory action. Furthermore, WS prophylaxis restored the activity levels of cytosolic antioxidant enzymes, neurotransmitter function and dopamine levels in st. Taken together, these findings suggest that WS prophylaxis has the propensity to modulate neurotoxicant-mediated oxidative impairments and mitochondrial dysfunctions in specific brain regions of mice. While the exact mechanism/s underlying the neuroprotective effects of WS merit further investigation, based on our findings, we hypothesize that it may be wholly or in part due to its ability to enhance GSH, thiols and antioxidant defences in the brain of mice.

Keywords: Brain, Mice, Mitochondrial dysfunctions, Oxidative stress, Parkinson’s disease, Rotenone, Withania somnifera