Abstract
Cognitive impairment is the major neurological challenge occurring due to degeneration of neurons in the brain. Raphanus sativus L. commonly called as radish showed antioxidant effect in hydrogen peroxide (H2O2) and hydroxyl radical scavenging assay. Phenytoin, an antiepileptic drug at a dose of 50 mg/kg was used to induce cognitive impairment in experimental animals. Piracetam was used as standard drug for complete study. Cognitive impairment in control group animals was established by decrease in inflexion ratio (elevated plus maze test), recognition index (novel object recognition test), fall off time (rotarod test) and increase in reaction time (cooks pole climbing test), escape latency (morris water maze test), transfer latency (rod walking test). These levels are restored to normal when treated with lower and higher doses of R. sativus. Later to explore molecular mechanism, biochemical parameters are estimated in mice brain. Increase in acetylcholinesterase (AChE) activity, lipid peroxidation (LPO) levels, nitric oxide (NO) levels and decreased glutathione (GSH), superoxide dismutase (SOD) levels are the indicators of cognitive impairment in control group animals. Piracetam 100 mg/kg, R. sativus 100 and 200 mg/kg are shown to restore all biochemical parameter levels near to normal, indicating cognitive improvement. Histopathological results also showed cognitive impairment, indicated by degeneration of neurons in hippocampus region of cerebral cortex. Piracetam treated animals showed normal morphology of brains without showing any apoptosis of neurons. Mild apoptosis was seen with R. sativus lower dose treatment. Whereas, in higher dose, no apoptosis of neurons is seen in cerebral cortex. Thus, R. sativus was found to increase learning and memory process by blocking apoptosis of neurons in cerebral cortex region. Effect of R. sativus is dose dependent. R. sativus 200 mg/kg was found to be statistically more significant than R. sativus 100 mg/kg. By taking an account of results of all these parameters, it is concluded that R. sativus is proved to possess cognitive improvement activity.