Wolfe M W, Roberson M S, Stumpf T T, Kittok R J, Kinder J E
Department of Animal Science, University of Nebraska, Lincoln 68583-0908.
J Anim Sci. 1992 Jan;70(1):248-53. doi: 10.2527/1992.701248x.
The objectives of the present study were 1) to determine whether 17 beta-estradiol (E2) regulation of tonic secretion of LH and FSH is sexually differentiated in the bovine and 2) to evaluate the effects of various physiological concentrations of E2 on the profiles and concentrations of gonadotropins in circulation. This was accomplished by administering different numbers of implants containing E2 to gonadectomized bovine males and females. Mean age at initiation of the study was 18.5 mo. Animals received 1, 2, 4, 8, or 16 implants of E2 or a sham implantation. Mean concentrations of LH in circulation and amplitude of LH pulses were similar between males and females after administration of E2. There was a cubic response for mean concentrations of LH and amplitudes of LH pulses across the dosages of E2 administered; lower concentrations of E2 had little effect, whereas higher concentrations of E2 suppressed both mean LH and amplitude of LH pulses. A linear decline in frequency of LH pulses occurred as concentrations of E2 in circulation increased. A treatment x sex interaction resulted for mean concentrations of FSH in circulation. Low doses of E2 resulted in a greater enhancement of circulating concentrations of FSH in males than in females. Tonic secretion of LH in bovine males and females responded in a similar manner to administration of various physiological concentrations of E2; however, a differential response between sexes was observed for FSH.
1）确定17β-雌二醇（E2）对牛促黄体生成素（LH）和促卵泡激素（FSH）的紧张性分泌调节是否存在性别差异；2）评估不同生理浓度的E2对循环中促性腺激素的分布和浓度的影响。这是通过给去势的公牛和母牛植入不同数量含E2的植入物来实现的。研究开始时的平均年龄为18.5个月。动物接受1、2、4、8或16个E2植入物或假植入。给予E2后，雄性和雌性循环中LH的平均浓度和LH脉冲幅度相似。在所给予的不同剂量E2中，LH的平均浓度和LH脉冲幅度呈三次方反应；较低浓度的E2影响不大，而较高浓度的E2会抑制LH的平均浓度和LH脉冲幅度。随着循环中E2浓度的增加，LH脉冲频率呈线性下降。循环中FSH的平均浓度出现了处理×性别的交互作用。低剂量的E2对雄性循环中FSH浓度的增强作用大于雌性。公牛和母牛的LH紧张性分泌对不同生理浓度E2的反应方式相似；然而，观察到两性对FSH的反应存在差异。
