Hypophysectomy facilitates sexual behavior in female rats.
Lordosis was elecited in 49% of 87 hormonally untreated, hypophysectomized-ovariectomized (hypox-ovx) female rats in response to palpation of the flanks and perineum (vaginal stimulation was not applied). By contrast, only 12% of 113 hormonally untreated ovariectomized (ovx) rats showed lordosis in response to such stimulation. Subsequently, hypox-ovx and ovx-only rats were given daily injections of 1 mug/kg estradiol benzoate (EB) and tested for sexual receptivity with males. Teh estrogen-treated hypox-ovx females became sexually receptive significantly earlier, and exhibited higher lordosis quotients and more soliciting behavior, than the estrogen-treated ovx-only rats. The increased sexual responsiveness in the hypox-ovx rats could be due to increased LRH activity. To test this, we treated hypox-ovx rats with dihydrotestosterone propionate (DHT-P), which suppresses plasma LH levels but is relatively ineffective in inducing sexual receptivity, and found a significant depression of lordosis responsiveness. These experiments suggest that hypox-ovx females show a heightened responsiveness to hormonal and/or sensory factors that induce a lordosis response, possibly because of increased LRH activity.
D000818:Animals; D001415:Back; D013196:Dihydrotestosterone / Q000031:analogs & derivatives / Q000494:pharmacology; D004958:Estradiol / Q000031:analogs & derivatives / Q000494:pharmacology; D005260:Female; D007016:Hypophysectomy; D008161:Lumbosacral Region; D010053:Ovary / Q000502:physiology*; D010502:Perineum; D010812:Physical Stimulation; D010902:Pituitary Gland / Q000502:physiology*; D011187:Posture; D051381:Rats; D012726:Sexual Behavior, Animal / Q000187:drug effects / Q000502:physiology*; D012879:Skin Physiological Phenomena
D013196:Dihydrotestosterone; D004958:Estradiol