Wolfe M W, Stumpf T T, Roberson M S, Wolfe P L, Kittok R J, Kinder J E
Animal Science Department, University of Nebraska, Lincoln 68583-0908.
Biol Reprod. 1989 Oct;41(4):626-34. doi: 10.1095/biolreprod41.4.626.
When ovaries are removed prior to puberty, administration of exogenous 17 beta-estradiol (E2) decreases concentrations of luteinizing hormone (LH) below that of ovariectomized heifers receiving no E2. Subsequent to the time age-matched intact heifers reach puberty, exogenous E2 increases secretion of LH in ovariectomized heifers above that of ovariectomized heifers receiving no E2. The hypothesis that E2 would inhibit gonadotropin secretion in bovine males during the time E2 no longer inhibited gonadotropin secretion in age-matched bovine females was tested. Males (n = 12) and females (n = 12) were gonadectomized at 241 +/- 3 days of age, and half of each sex (6 males and 6 females) were administered a 27-cm E2 implant. An additional group of males (n = 6) and females (n = 6) remained intact and served as controls. Blood samples were collected (to quantify LH and follicle-stimulating hormone [FSH]) from all animals at 15-min intervals for 24 h at 1, 7, 13, 17, 21, 25, 29, 33, 37, and 43 wk after gonadectomy. Additional blood samples were collected twice weekly from control females to monitor progesterone and onset of corpus luteum function (451 days of age). E2 inhibited frequency of pulses of LH (p less than 0.01) and decreased mean concentration of LH and FSH (p less than 0.01) at Week 1 in gonadectomized males treated with E2 compared to gonadectomized males not administered E2.(ABSTRACT TRUNCATED AT 250 WORDS)
在青春期前切除卵巢后，给予外源性17β-雌二醇（E2）可使促黄体生成素（LH）浓度降至未接受E2的去卵巢小母牛之下。在年龄匹配的完整小母牛进入青春期后，外源性E2可使去卵巢小母牛的LH分泌量高于未接受E2的去卵巢小母牛。我们检验了这样一个假设：在E2不再抑制年龄匹配的雌性牛的促性腺激素分泌时，E2会抑制雄性牛的促性腺激素分泌。雄性（n = 12）和雌性（n = 12）在241±3日龄时进行性腺切除，每种性别各有一半（6只雄性和6只雌性）植入27厘米的E2植入物。另外一组雄性（n = 6）和雌性（n = 6）保持完整作为对照。在性腺切除后1、7、13、17、21、25、29、33、37和43周时，每隔15分钟采集所有动物的血样（以定量LH和促卵泡生成素[FSH]），持续24小时。每周两次从对照雌性动物采集额外的血样，以监测孕酮和黄体功能的开始（451日龄）。与未给予E2的去势雄性相比，给予E2的去势雄性在第1周时，E2抑制了LH脉冲频率（p<0.01），并降低了LH和FSH的平均浓度（p<0.01）。（摘要截于250字）
