Infusions of cholecystokinin-octapeptide into the ventral tegmental area enhance the reinforcing effects of amphetamine

Abstract

The objectives of the present study were to behaviorally and neurochemically investigate reinforcing properties of the neuropeptide cholecystokinin (CCK) in the ventral tegmental area (VTA). CCK infusions into the VTA significantly potentiated the reinforcing effects of amphetamine. CCK did not, by itself, have reinforcing or aversive effects at any dose tested (0.0, 0.04. 0.4 and 4.0 nanograms/cannula). Furthermore, infusions of CCK into the VTA did not significantly affect basal or amphetamine-enhanced depletion of DA in caudate or in three regions of the N ACC following administration of a tyrosine hydroxylase inhibitor. Results of the present dissertation indicate that (1) CCK may functionally interact with dopaminergic mechanisms in facilatory manners which do not enhance DA release and (2) that sites of action for CCK may exist in the VTA.