Abstract

Neuroprotective effects of two medicinally important herbs Withania somnifera (WS) andAsparagus racemosus (AR) were investigated in primary hippocampal neuron cell culture. The root extracts of WS and AR were obtained by Soxhlet extraction using distilled water as solvent. The 7 to 8 days old hippocampal cells in culture were treated with100 µM Glutamate (Glu) for 10 min at room temperature in Hank's balanced saline solution (HBSS). One hour (1 h) after exposure to Glu, cells were treated with root extract of WS, AR or WS + AR [10 µg/ml dissolved in dimethyl sulfoxide (DMSO)], respectively. Results of the study suggested that percent cell viability [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay] was more significant in groups treated with Glu + WS and Glu + WS + AR, when compared to group treated with Glu + AR. More than two-fold increase in free Ca²⁺ was observed in culture in presence of Glu, but after treatment with WS, this increase was significantly reduced (P < 0.01). No significant change was observed in presence of AR. A significant decrease in lactic dehydrogenase (LDH) was observed after WS, AR as well as WS + AR, when compared with Glu treated group. There was significant (P < 0.01) decrease in malondialdehyde (MDA) in presence of WS or AR. Reactive oxygen species (ROS) level was significantly inhibited in both Glu + WS and Glu + AR treated group, compared to Glu and Glu + WS + AR treated group. Significant elevation of reduced glutathione (GSH) and glutathione disulfide (GSSG) was also obtained after WS and AR treatment. A marked increase in nerve growth factor (NGF) and pro-brain derived growth factor (pro-BDNF) expression was observed after AR and WS + AR treatment; whereas no observable change was observed in WS treated group. It was therefore, concluded thatboth plants in combination (WS + AR) have more effective role in neuroprotection. Study also showed neurotrophic factor modulatory activity of these plants. Present study suggest that WS + AR in combination could have alternative therapeutic potency for treatment of diseases associated with neuron cell loss.

Key words: Withania somnifera, Asparagus racemosus, hippocampus, glutamate, in vitro, neuroprotection.