Dopamine antagonism attenuates the unconditioned incentive value of estrous female cues.

The role of dopaminergic transmission in the incentive-motivational processes involved in the generation of male sexual behavior was examined. Three groups of sexually naïve Long-Evans male rats traversed a straight alley for one of three goalbox targets: an empty goalbox, a nonestrous female, or an estrous female. A Plexiglas partition within the goalbox allowed for the perception of visual, auditory, and olfactory cues, but prevented physical contact. Baseline run times revealed that subjects returned to the goalbox significantly faster for an estrous female than for a nonestrous female, replicating our earlier work on the inherent incentive value of primary female cues. When subjects were then pretreated with the dopamine receptor antagonist, haloperidol (0.0, 0.075, or 0.15 mg/kg), they expressed decreased sexual motivation as reflected by increased run times for estrous female targets. Subjects' run times for the empty goalbox condition were unaffected by haloperidol, suggesting that the drug did not reliably impair motoric capacity. Results support the contention that central dopaminergic systems are involved in the regulation of the positive, unconditioned incentive value of estrous female cues.