EXCITATORY EFFECTS OF DOPAMINE RELEASED BY IMPULSE FLOW IN THE RAT NUCLEUS-ACCUMBENS IN-VIVO

Dopamine is generally considered to be an inhibitory neurotransmitter in the central nervous system.(2,4,5,7,9,14,18,19,21,22,25,31,32) Dopa mine release in the nucleus accumbens can be evoked by chemical stimul ation of the afferent cell bodies using N-methyl-D-aspartate microinje ction in the ventral tegmental area.(12,26) We report here that follow ing such injections area, most neurons of the nucleus accumbens were e xcited, This excitation was abolished if dopaminergic neurons were les ioned and was blocked by antagonists of the D-1 dopamine receptors, Fi nally, excitatory responses to electrical stimulation of the hippocamp us were strongly facilitated by endogenously released dopamine. We sug gest, therefore, that under physiological conditions, dopamine acting on D-1 receptors is actually an excitatory neurotransmitter. Copyright (C) 1996 IBRO.