SEROTONIN POTENTIATES DOPAMINE INHIBITION OF VENTRAL TEGMENTAL AREA NEURONS IN VITRO. Brodie, Mark S., E. Bradshaw Bunney. Department of Physiology and Biophysics, University of Illinois at Chicago, College of Medicine, Chicago, IL 60612 U.S.A. and Department of Emergency Medicine, University of Illinois at Chicago, College of Medicine, Chicago, IL 60612 U.S.A..
APStracts 3:0117N, 1996.
1. The ventral tegmental area (VTA) has been implicated in both the rewarding effects of drugs of abuse and the etiology of schizophrenia. We report here that serotonin potentiates the inhibitory effect of dopamine on dopaminergic VTA neurons. Dopamine (0.5 - 10 [mu]M) inhibited the spontaneous firing of putative dopamine-containing neurons of the VTA. Serotonin (5 - 10 [mu]M) itself did not significantly alter the spontaneous firing rate; however, in the presence of serotonin, the inhibitory potency of dopamine was significantly increased. 2. The inhibitory potency of the dopamine agonist quinpirole was also increased by serotonin. 3. Serotonin-induced potentiation was also produced by the selective 5-HT 2 agonist, DOI ((+/-)-2,5-dimethoxy-4- iodoamphetamine), and was reversed by the selective 5-HT 2 antagonist ketanserin. 4. This novel action of serotonin on dopaminergic neurons has important implications for the development of drugs to treat schizophrenia, and for the identification of agents which will be useful in treating drug abuse disorders like alcoholism.

Received 18 April 1996; accepted in final form 5 June 1996.
APS Manuscript Number J325-6.
Article publication pending J. Neurophysiol.
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 17 June 96