Enhancement of memory function by antioxidant potential of Nigella sativa L. oil in restrained rats

Stress is a vulnerable state to cellular homeostasis which leads to oxidative damage via free radical generation. The acute stress induces alteration in antioxidant enzyme activities to an extent which produce oxidative stress and causes certain pathological conditions. The use of Nigella sativa L. oil (NSO) in folk medicine has increased throughout the world for the prevention or treatment of various ailments because of potent antioxidant properties. In the present study, potential therapeutic effects of NSO on memory in both unrestrained and 2h restrained rats were observed. Shortterm memory (STM) and long-term memory (LTM) were assessed by elevated plus maze (EPM) and Morris water maze (MWM) respectively. The present study also demonstrated the effect of NSO on lipid peroxidation (LPO) and activities of antioxidant enzymes (superoxide dismutase, catalase and glutathione peroxidase) along with the activity of acetyl cholinesterase (AChE). The results obtained from the present study showed that 2h restraint stress significantly enhanced both short-term memory (p<0.01) and long-term memory (p<0.05) in rats. Pretreatment with NSO at a dose of 0.2ml/kg/day also significantly improved STM (p<0.05) in restrained rats and LTM (p<0.01) in unrestrained rats. This study also showed significantly decreased (p<0.01) LPO and significantly increased (p<0.01) endogenous antioxidant enzymes activity in NSO treated restrained rats. Similarly significant decreased (p<0.01) AChE activity was also observed in NSO treated unrestrained and 2h restrained rats. Therefore, current findings suggested that repeated administration of NSO may exert memory enhancing effects against restrained stress and it can be used for therapeutic purpose because of having fewer side effects.