Luteinizing Hormone-Releasing Hormone and Thyrotropin-Releasing Hormone Induction of Female Sexual Receptivity in the Lizard, Anolis carolinensis

Abstract

Both luteinizing hormone-releasing hormone (LHRH) and thyrotropin-releasing hormone (TRH) induce sexual receptivity in ovariectomized, estrogen-primed female lizards (Anolis carolinensis). Ovariectomized females pretreated with three daily injections of a subthreshold dose (0.2 μg) of estradiol benzoate were administered either 500, 1,000 or 1,500 ng of LHRH, or 1,000 ng of TRH 48 h following the last estrogen pretreatment injection. Hormone-treated females exhibited significantly higher sexual receptivity scores than controls when tested 2, 4, 6 and 24 h post-injection. Female sexual receptivity scores in females that were administered 500 ng of LHRH or 1,000 ng of deamido TRH were, however, no different than control scores at these test times. The observed ability of LHRH to increase female sexual receptivity is consistent with previous results in birds and mammals. The ability of TRH to increase female sexual receptivity is a novel finding that may underscore differences in neuroendocrine regulation of vertebrate estrous behavior.