Rheum Turkestanicum Reduces Glutamate Toxicity in PC12 and N2a Cell Lines

Glutamate, as an important endogenous excitatory neurotransmitter, has major physiological functions in the central nervous system. Nevertheless, glutamate accumulation may result in neuronal damage and cell death under different pathological conditions via various mechanisms, mainly oxidative damage and excitotoxicity. Materials and Methods: In this study, we investigated the neuroprotective effectsof Rheum turkestanicum in the glutamate-induced rat pheochromocytoma (PC12 cells) and mouse neuroblastoma (N2a) cell lines. Rutin as an antioxidant was used as positive control. For MTT/ROS and MDA assays, the cells were respectively cultured in 96- and 24-well plates, and for apoptosis assays, the cells were seeded in 24-well plates (100 000 cells/well); it should be noted that all treatments were performed in triplicate. For two hours, the cells were pretreated with only the extract (6-200 μg/mL). Incubation was carried out with the extract for 24 hours, with or without glutamate (8 mM). Finally, rutin was used to pretreat the cells for two hours, and then, incubation was performed with glutamate for 24 hours. Results: Glutamate cytotoxicity was accompanied by an increment of malondialdehyde (MDA) content, ROS generation and apoptosis induction. However, pretreatment with the root extract of Rheum turkestanicum significantly reduced MDA content, ROS generation and apoptotic cell death. Also rutin at dose of 100 μM reduced ROS production and protected against glutamate toxicity. Also the quantification of rutin in R.turkestanicum extract was achieved and was about 0.11 % ± 0.01 w/w. Conclusion: All thesefindings indicated that R. turkestanicum protected PC12 and N2a cells against glutamate-induced oxidative cell death and apoptosis and might raise the possibility of R. turkestanicum usage as a neuroprotective agent.