Majumdar S S, Winters S J, Plant T M
Department of Cell Biology, University of Pittsburgh School of Medicine, Pennsylvania 15261, USA.
Endocrinology. 1997 Apr;138(4):1363-73. doi: 10.1210/endo.138.4.5058.
The purpose of this study was to examine the relative roles of FSH and LH in stimulating testicular inhibin secretion in the male rhesus monkey. Recombinant human (rh) FSH and rhCG were used as the gonadotropic stimuli, and juvenile rhesus monkeys, in which the endocrine activity of the pituitary-testicular axis was being driven in an adult manner with an intermittent i.v. GnRH infusion, were studied. Immunoactive inhibin levels were measured by the Monash RIA. Initiation of an intermittent i.v. infusion of rhFSH (10 IU every 3 h) resulted, after a delay of 5-6 h, in a progressive increase in the concentrations of immunoactive inhibin, which achieved, after 48 h of stimulation, a value twice that observed during vehicle treatment. Gel filtration chromatography revealed that the FSH-induced elevation in immunoactive inhibin was the result of an increase in three distinct mol wt fractions: peak I (100 kDa), peak II (50-60 kDa), and peak III (31 kDa). Although peak III accounted for most of the inhibin immunoactivity in vehicle-treated animals, peaks I and II were most responsive to FSH stimulation. Application of recently developed enzyme-linked immunosorbent assays for inhibin B and pro-alpha-C-related peptides provided additional insights into the nature of the FSH-sensitive forms of circulating immunoactive inhibin. Most notably, the 31-kDa fraction (peak III) was comprised of inhibin B and pro-alpha-C. In contrast to FSH stimulation, an intermittent infusion of rhCG (40 IU every 3 h), which markedly elevated testicular testosterone secretion, failed to increase immunoactive inhibin concentrations. These findings indicate that various forms of immunoactive inhibin are present in the circulation of the rhesus monkey, and that in this species, FSH is the principal stimulus of the secretion of testicular inhibins, including inhibin B. Additionally, they further underline the importance of the FSH-inhibin feedback loop in governing testicular function in primates.
本研究的目的是检测促卵泡激素（FSH）和促黄体生成素（LH）在刺激雄性恒河猴睾丸抑制素分泌中的相对作用。使用重组人（rh）FSH和rhCG作为促性腺激素刺激物，并对幼年恒河猴进行研究，这些幼年恒河猴通过间歇性静脉注射促性腺激素释放激素（GnRH）以成年方式驱动垂体 - 睾丸轴的内分泌活动。免疫活性抑制素水平通过莫纳什放射免疫分析法（Monash RIA）进行测量。间歇性静脉注射rhFSH（每3小时10 IU）开始后，经过5 - 6小时的延迟，免疫活性抑制素浓度逐渐升高，在刺激48小时后达到的值是在注射赋形剂治疗期间观察到的值的两倍。凝胶过滤色谱显示，FSH诱导的免疫活性抑制素升高是三种不同分子量组分增加的结果：峰I（100 kDa）、峰II（50 - 60 kDa）和峰III（31 kDa）。虽然峰III在注射赋形剂治疗的动物中占抑制素免疫活性的大部分，但峰I和峰II对FSH刺激最敏感。应用最近开发的抑制素B和前α - C相关肽的酶联免疫吸附测定法，为循环免疫活性抑制素的FSH敏感形式的性质提供了更多见解。最值得注意的是，31 kDa组分（峰III）由抑制素B和前α - C组成。与FSH刺激相反，间歇性注射rhCG（每3小时40 IU）可显著提高睾丸睾酮分泌，但未能增加免疫活性抑制素浓度。这些发现表明，恒河猴循环中存在多种形式的免疫活性抑制素，并且在该物种中，FSH是睾丸抑制素（包括抑制素B）分泌的主要刺激物。此外，它们进一步强调了FSH - 抑制素反馈回路在控制灵长类动物睾丸功能中的重要性。
