Relation of spontaneous wet dog shakes and copulatory behavior in male rats

Pharmacological manipulation of 5-HT2 activity has yielded equivocal effects on male rat sexual behavior. Both facilitation and inhibition of copulation have been reported following treatment with 5-HT2 antagonists. "Wet dog shake" (WDS), a component of the Serotonin Behavioral Syndrome, is largely mediated by 5-HT2 receptors. The present series of experiments were aimed at determining whether WDS might yield a spontaneous behavioral measure of 5-HT2 activity that converges on the pharmacological data. In Experiment 1, spontaneous WDS was recorded in 58 male rats paired with receptive females. Normal copulators (Studs) exhibited significantly less WDS than did noncopulators (Duds). In Experiment 2, the males were additionally paired with males and nonreceptive females. In these situations, WDS did not discriminate Duds from Studs, but Studs scores differed from each other across the three different partner conditions. Lastly, in Experiment 3, treatment with the selective 5-HT2 agonist DOI potently inhibited copulatory responses and increased WDS. Overall, the data from the three experiments suggest that 5-HT2 activity mediates an inhibition of male rat sexual behavior.