Nerve Growth Factor로 분화된 PC12세포에서 Glutamate성 독성에 대한 보호

Abstract

Glutamate is a primary excitatory neurotransmitter in the mammalian central nervous system, however excitotoxic when in excess. This study was designed to evaluate the mechanism of the glutamatergic excitotoxicity and the effect of several protective agents which are known to interupt the intracellular apoptotic processes. The excitotoxicity was induced in nerve growth factor (NGF) - differentiated PC12 cells by adding 10 mM glutamate. In the cells treated with 10 mM glutamate, the cell number was decreased and the neurites were markedly shrunken. Cell viability was about a half determined by MTT test. Ionotropic glutamate receptor antagonists, AP5 (20 µM), MK801 (10 µM), and CNQX (20µM) in a single or combined treatments did not improve the viability of the excitotoxic PC12 cells. Antiapoptotic agents, cyclosporin A (0.5 µM) and Z-VAD-fmk (100 µM) did not improve the viability of the excitotoxic PC12 cells. However antioxidant, Cu/Zn superoxide dismutase (5~50 U) completely recovered the viability of the excitotoxic PC12 cells. Inhibitors of intracellular stored Ca2+ release, ryanodine (100µM) and U73122 (2µM), partially improved the cell viability only in the combined treatments with NMDA receptor antagonist, MK801. In conclusion, metabotropic glutamate receptors seems to participate in the increase of intracellular Ca2+ together with NMDA receptors in the excitotoxic process of NGF differentiated PC12 cells. Glutamatergic neuronal toxicity is mainly associated with the excess production of oxygen free radicals.