NITRIC-OXIDE REGULATES NMDA-INDUCED DOPAMINE RELEASE IN RAT STRIATUM

WE investigated the effect of nitric oxide (NO) on N-methyl-D-aspartat e (NMDA)-induced changes in levels of dopamine (DA) and its metabolite in the striatum using in vivo microdialysis. Local administration of 1 mM NMDA into the striatum significantly augmented DA release in the striatum. Simultaneous administration of 5 mM NG-nitro-L-arginine meth yl ester (-NAME), a NO synthase inhibitor, into the striatum significa ntly potentiated NMDA-induced DA release. This effect of L-NAME was co mpletely reversed in the presence of 50 mM L-arginine (L-Arg). Adminis tration of 1 mM NMDA significantly decreased the levels of dihydroxyph enylacetic acid (DOPAC) and homovanillic acid (HVA). This effect of NM DA was not affected by concurrent administration of L-NAME. This study provides in vivo evidence for the involvement of NO in NMDA-induced D A release.