CHOLECYSTOKININ MODULATES MESOLIMBIC DOPAMINERGIC INFLUENCES ON MALE-RAT COPULATORY-BEHAVIOR

Much evidence suggests that the neuropeptide cholecystokinin (CCK) fun ctions as a neurotransmitter or neuromodulator in the central nervous system. The CCKa receptor subtype in the nucleus accumbens has been de monstrated to potentiate the behavioral and neurophysiological effects of dopamine. Since the mesolimbic dopamine system participates in the regulation of male rat sexual behavior, the present investigation was undertaken to determine if central CCK modulates this dopaminergic re gulation. Electrical stimulation of the ventral tegmental area greatly enhanced several measures of appetitive and consummatory male rat sex ual behavior. Administration of a CCKa receptor antagonist to the post eromedian nucleus accumbens reversed the electrically stimulated behav ioral enhancement. A CCKb antagonist was without effect. In a second g roup of animals, administration of either a CCKa or CCKb antagonist to the anterolateral nucleus accumbens reversed the enhancement of consu mmatory sexual responding produced by electrical stimulation. These re sults agree with the growing body of evidence supporting different beh avioral roles for two distinct CCK systems in the nucleus accumbens.