Hormone Release during Mating in the Male Rat: Time Course, Relation to Sexual Behavior, and Interaction with Handling Procedures*

Abstract

The time course of hormone release was studied in male rats which mated with receptive females for 60-120 min. In response, males exhibited rapid increases in plasma LH [lutropin] and PRL [prolactin] levels, which peaked 5-15 min after the initiation of mating. Testosterone (T) levels rose more slowly and peaked at 30-60 min. FSH [follitropin] levels did not change during mating. Similar patterns of hormone release were observed whether blood was collected from etherized rats by decapitation or from unanesthetized rats via indwelling atrial cannulae. When rats were ranked in terms of their relative speed in achieving multiple ejaculations, fast and slow maters did not differ in either the pattern or the magnitude of hormone release during mating. Hormone release was not related to particular behavior events in the mating sequence. Rats which showed no interest in the female also showed no elevations in hormone levels during exposure to a female. Transfer to an empty mating arena produced slight increases in LH and T levels but did not alter PRL levels. The response to transfer was eliminated in rats bled via cannulae; these rats were not handled before or during blood collection. Hormone release is independent of both sexual performance and particular behavioral events in mating rats, but does depend on their sexual motivation. The hormonal response to sexual stimulation is specific, since it can be distinguished from the response to transfer.