NITRIC-OXIDE FACILITATES N-METHYL-D-ASPARTATE-INDUCED BURST FIRING INDOPAMINE NEURONS FROM RAT MIDBRAIN SLICES

Dopamine (DA) neurons in the ventral tegmental area and substantia nig ra pars compacta were induced to fire in bursts with application of N- methyl-D-aspartate (NMDA, 20 mu M) and apamin (100 nM) while recording intracellularly in the rat brain slice. L-Arginine (300 mu M), a subs trate for nitric oxide (NO) production, increased both the number of s pikes per burst and the magnitude of interburst hyperpolarizations. Ni tric oxide synthase inhibitors N-nitro-L-arginine methyl ester (L-NAME , 100 mu M), N-nitro-L-arginine, and 7-nitroindazole inhibited NMDA-in duced burst firing by reducing the number of spikes per burst. Moreove r, L-arginine (100 mu M) reversed the inhibition of burst firing produ ced by L-NAME. These findings suggest that NO facilitates NMDA-induced burst firing in DA neurons. (C) 1998 Elsevier Science Ireland Ltd. Al l rights reserved.