Effects of 5-HT1A selective anxiolytics on lordosis behavior: interactions with progesterone.

Ipsapirone and gepirone, but not buspirone, facilitated lordosis in estrogen-treated rats, whereas all three drugs inhibited this behavior in rats treated with estrogen and progesterone. When administered at higher doses, ipsapirone, gepirone and buspirone inhibited lordosis in rats treated with either estrogen or estrogen and progesterone. These data are consistent with the proposal that 5-HT1A receptors mediate lordosis-inhibiting effects of 5-HT, and further suggest that some 5-HT1A agonists may facilitate lordosis by activity at autoreceptors. Finally, these data show that progesterone may modulate activity at 5-HT1A receptors.