Leptin facilitates lordosis behavior through GnRH-1 and progestin receptors in estrogen-primed rats

Abstract

Dose response curves for leptin facilitation of estrous behavior (lordosis and proceptivity) were made by infusing the peptide into the lateral ventricle (icv) of ovariectomized (ovx), ad libitum-fed rats injected 40 h previously with 5 mu g of estradiol benzoate. Leptin doses of 1 and 3 mu g produced significant lordosis quotient at 60 min post-injection, with maximal lordosis being displayed at 120 min. Yet the intensity of lordosis was weak, and a high incidence of rejection behaviors was found. Moreover, leptin did not induce significant proceptive behaviors at any dose. The leptin doses of 1 and 3 mu g were selected for determining whether antide, a GnRH-1 receptor antagonist, or the progestin receptor antagonist RU486 could modify the lordosis response to leptin. Icv injection of either antide or RU486 1 h before leptin significantly depressed leptin facilitation of lordosis. The results suggest that leptin stimulates lordosis by releasing GnRH, which in turn activates GnRH-1 and progestin receptors. The physiological role of leptin in the control of estrous behavior remains to be determined. (c) 2010 Elsevier Ltd. All rights reserved.