EXTRACELLULAR DOPAMINE IN THE MEDIAL PREOPTIC AREA - IMPLICATIONS FORSEXUAL MOTIVATION AND HORMONAL-CONTROL OF COPULATION

Dopamine (DA) activity in the medial preoptic area (MPOA) contributes to the control of mate rat sexual behavior, We tested (1) whether extr acellular DA increases during precopulatory exposure to an estrous fem ale and during copulation, (2) whether exposure to another male increa ses extracellular DA, (3) whether motor activity during copulation acc ounts for increased DA levels, and (4) whether concurrent or recent te stosterone influences DA levels or copulation in castrates, Extracellu lar DA and its metabolites in male rats' MPOA were measured using micr odialysis, DA levels increased during precopulatory exposure to the fe male in all animals that subsequently copulated; this included all int act animals, all testosterone-treated castrates, and 9 of 14 1-week ca strates treated with oil vehicle, DA levels did not increase in any an imal that subsequently failed to copulate, including the remaining 1-w eek, and all 2-week, vehicle-treated castrates, When the barrier was r emoved and the animals were allowed to copulate, levels of DA and its metabolites continued to rise in intact males and in castrates that co pulated. The DA response to the estrous female could not be attributed to nonsexual social stimuli, since exposure to another male was ineff ective, The DA response to copulation could not be attributed primaril y to motor activity, since animals running voluntarily in a running wh eel did not show significantly increased DA. These and previous data s uggest that DA released in the MPOA in response to an estrous female m ay contribute to sexual motivation and copulatory proficiency. Testost erone may promote copulation in part through permissive actions on dop amine release.