LHRH and mating behavior: sexual receptivity versus sexual preference

Sexual behavior and sexual preference measurements were obtained from ovariectomized female rats treated with estrogen, estrogen and progesterone, or estrogen followed by third ventricular infusion of luteinizing hormone releasing hormone (LHRH) or saline. The lordosis-to-mount ratio and the occurrence of receptive and proceptive behaviors were scored to assess total sexual receptivity. Sexual preference was determined by placing the test female in the center of a four-winged choice box apparatus in which each of the outer wings contained one of the following incentive animals: a sexually active male (SM), a castrate male (CM), a female in proestrus (PF), and an ovariectomized female (OF). Time spent in close proximity to the incentive animals was measured as an index of sexual preference. Estrogen and progesterone treatment resulted in high sexual receptivity and a marked preference for SM. Estrogen alone or in combination with saline also produced a significant preference for SM. Animals treated with estrogen and LHRH exhibited high levels of sexual receptivity compared to estrogen saline treated controls, but no enhancement of preference for SM was detected. The results indicate that fractionation of sexual receptivity and sexual motivation occurs following estrogen-LHRH treatment.