A comparative study of different amphetamines on copulatory behavior and stereotype activity in the female rat.

The influence of D- and L-amphetamine, fenfluramine, and p-chloroamphetamine on female copulatory behavior (lordosis response) and the induction of stereotype activity was compared. Lordosis response in the female rat has been shown to be inhibited by increased central nervous serotonergic (5-HT) as well as dopaminergic (DA) activity. A dose-dependent inhibitory effect on the estrogen- + progesterone-induced lordosis response in ovariectomized rats was demonstrated after treatment with the four amphetamines. In contrast, only D- and L-amphetamine induced a stereotype activity, which is considered to be mediated by DA mechanisms. A decrease in DA receptor activity, achieved by pimozide pretreatment, abolished the effect of D-amphetamine on lordosis behavior, but the effect of L-amphetamine was only slightly diminished and the action of fenfluramine and p-chloroamphetamine was unaffected. On the other hand, both L- and D-amphetamine-induced stereotype activity was prevented by pimozide treatment. The data suggest that the D-amphetamine effect on lordosis behavior is mediated by increased DA receptor activity. Although it induces stereotype activity by increased DA activity, L-amphetamine, like fenfluramine and p-chloroamphetamine, inhibits the lordosis response by some other action presumably related to serotonergic mechanisms.