NMDA-receptors are involved in Cu2+/paraquat-induced death of cultured cerebellar granule neurons

Rat cultured cerebellar granule neurons (CGNs) were not sensitive to CuCl2 (1-10 A mu M, 24 h), whereas paraquat (150 A mu M) decreased neuronal survival to 79 +/- 3% of control level. Simultaneous treatment of CGNs with paraquat and CuCl2 (2, 5, or 10 A mu M Cu2+/paraquat) caused significant copper dose-dependent death, lowering their survival to 56 +/- 4, 37 +/- 3, or 16 +/- 2%, respectively, and stimulating elevated production of free radicals in CGNs. Introduction of vitamin E, a non-competitive antagonist of NMDA subtype of glutamate receptors (MK-801), and also removal of glutamine from the incubation medium decreased toxicity of Cu2+/paraquat mixture. However, addition of Cu2+ into the incubation medium did not affect CGNs death caused by glutamate. These data emphasize that excessive copper in the brain may trigger oxidative stress, which in turn results in release of glutamate, overstimulation of glutamate receptors, and neuronal death.