Endocrine Mechanisms Governing Transition into Adulthood: A Marked Decrease in Inhibitory Feedback Action of Estradiol on Tonic Secretion of Luteinizing Hormone in the Lamb during Puberty

摘要: The hypothesis was tested that a decrease in response to the inhibitory feedback action of estradiol on tonic LH secretion occurs female lamb during puberty. Ovaries were removed from 10 lambs at 19 weeks age, which approximately 11 before expected first ovulation. At ovariectomy, Silastic implants containing crystalline inserted sc 6 maintain chronic low levels circulating estradiol. In estradiol-treated ovariectomized lambs, serum suppressed undetectable concentrations until age when ovulations initiated untreated intact lambs. this time, increased dramatically castrate 5 females despite maintenance constant ”escape“ negative and ovulation occurred over wide range body weights. slowest growing estradiol-treat...