Dopaminergic drugs in the medial preoptic area and nucleus accumbens: effects on motor activity, sexual motivation, and sexual performance.

In two experiments, dopamine agonists and/or antagonists were injected into the medial preoptic area (MPOA) or the nucleus accumbens (NAcc) of male rats. The animals were then tested in an X-mase with four goal boxes, which contained a receptive female, a male, or were empty. In Experiment 1, the D1 antagonist SCH-23390 and the D2 antagonist raclopride in the MPOA decreased the percentage of trials on which the female's chamber was chosen, a measure of sexual motivation. Raclopride also decreased the number of animals that copulated after choosing the female's chamber. The 10-micrograms dose of the D3/D2 agonist quinelorane increased the latency to reach the female's chamber, slowed the onset of copulation, and decreased the number of intromissions preceding an ejaculation. In Experiment 2, 1- and 5-micrograms doses of quinelorane and of the mixed D1/D2 agonist apomorphine were injected bilaterally into the NAcc. Both doses of quinelorane increased the number of times that the subject did not select a chamber within 60 s. No drug in the NAcc affected specifically sexual motivation or performance. The results are consistent with differential influence of the MPOA and the NAcc on motor activity, sexual motivation, and sexual performance.