Department of Psychology, Southwestern University, Georgetown, TX 78626, USA.
Department of Psychology, Southwestern University, Georgetown, TX 78626, USA.
Horm Behav. 2021 Jun;132:104982. doi: 10.1016/j.yhbeh.2021.104982. Epub 2021 May 3.
The present study was designed to examine the effects of suppressing pubertal onset with leuprolide acetate, a gonadotropin releasing hormone (GnRH) agonist. Starting on postnatal day (PD) 25, male Long-Evans rats were injected daily with either leuprolide acetate (25 μg/kg dissolved in 0.9% sterile physiological saline; n = 13) or sterile physiological saline (1.0 ml/kg 0.9% NaCl; n = 14) for a total of 25 days. Males were monitored daily for signs of puberty (i.e., preputial separation). On the last day of leuprolide treatment (PD 50), half of each treatment group was injected with 10.0 μg of estradiol benzoate (EB) daily for three consecutive days (PD 50-52) and 1.0 mg of progesterone (P) on the 4th day (PD 53), whereas the other half of each treatment group received oil injections. Four hours after P injections, all subjects were given the opportunity to interact with a gonadally-intact male and a sexually receptive female rat (i.e., a partner-preference test with and without physical contact). Copulatory behavior and sexual motivation were measured. Hormone injections and mating tests were repeated weekly for a total of 3 consecutive weeks. Results showed that leuprolide delayed puberty as well as the development of copulatory behavior and the expression of sexual motivation. By the last test, the leuprolide-treated subjects showed signs of catching up, however, many continued to be delayed. Estradiol and progesterone mildly feminized male physiology (e.g., decreased testes weight and serum testosterone) and behavior (e.g., increased lordosis), but did not interact with leuprolide treatment.
本研究旨在探讨使用促性腺激素释放激素（GnRH）激动剂亮丙瑞林抑制青春期启动对雄性 Long-Evans 大鼠的影响。从出生后第 25 天（PD）开始，雄性大鼠每天接受亮丙瑞林（25μg/kg 溶于 0.9%无菌生理盐水；n=13）或无菌生理盐水（1.0ml/kg 0.9%NaCl；n=14）注射，共 25 天。雄性大鼠每天监测青春期的迹象（即包皮分离）。在亮丙瑞林治疗的最后一天（PD50），每组的一半接受 10.0μg 的苯甲酸雌二醇（EB）连续三天（PD50-52）注射，另一半接受油注射。在第 4 天（PD53）注射 1.0mg 的孕酮（P）。P 注射后 4 小时，所有动物都有机会与一只去势雄性大鼠和一只发情雌性大鼠进行互动（即有无身体接触的伴侣偏好测试）。测量交配行为和性动机。激素注射和交配测试每周重复一次，共进行 3 周。结果表明，亮丙瑞林不仅延迟了青春期的出现，还延迟了交配行为和性动机的发展。在最后一次测试中，亮丙瑞林处理的大鼠表现出追赶的迹象，但许多大鼠仍持续延迟。雌二醇和孕酮轻度使雄性大鼠的生理（如睾丸重量和血清睾酮减少）和行为（如背躬反射增加）女性化，但与亮丙瑞林处理无相互作用。
