The effect of ketanserin on lordosis behavior after intracranial infusion into the ventromedial nucleus of the hypothalamus

Recent evidence has led to the suggestion that the ventromedial nucleus of the hypothalamus (VMN) is an effective site for the inhibitory effects of the 5-HT1A receptor agonists on lordosis behavior. 5-HT2A12c receptor agonists facilitate, and antagonists inhibit, lordosis behavior, but the neural location for the 5-HT2 A12c receptor modulation is unknown. In the following experiment, proestrous rats were infused intracranially with 500 ng, 1000 ng or 3000 ng of ketanserin tartrate and sexual behavior was examined for 30 min thereafter. There was a dose-dependent decline in both lordosis frequency and lordosis quality following infusion with the 5-HT 2A12c receptor antagonist. Thus 5-HT appears to exert both an inhibitory and a facilitatory effect within the VMN.