Vihko K K, LaPolt P S, Nishimori K, Hsueh A J
Department of Gynecology and Obstetrics, Stanford University Medical Center, California 94305.
Endocrinology. 1991 Oct;129(4):1926-32. doi: 10.1210/endo-129-4-1926.
Although earlier reports suggest a stimulatory effect of FSH on Leydig cell function, controversy exists due to unavailability of FSH preparations free of contaminating LH. Recent availability of recombinant human FSH preparations made it possible to reinvestigate this question. Immature male rats were hypophysectomized (21-22 days old at surgery) and implanted with osmotic minipumps releasing 8 IU recombinant FSH or 18 IU purified human pituitary FSH (hpFSH)/day, whereas control animals received vehicle alone. After 7 days of treatment, testicular weight increased in the recombinant FSH and hpFSH-treated animals to values 2.3- and 2.5-fold those of controls, respectively. Analyses of the steroidogenic capacity of Leydig cells in testes of rats treated with recombinant FSH or hpFSH also revealed 2.9- and 3.8-fold androgen production in vitro compared to controls. In these rats recombinant FSH and hpFSH increased the LH receptor number in testicular homogenate by 50% and 70%, respectively. The increase in LH receptor number was associated with increases in the LH receptor mRNA levels. In hypophysectomized control rats, small seminiferous tubules contained spermatogonia and zygotene/early pachytene spermatocytes. In contrast, treatment with either FSH preparation enhanced the progression of meiosis, as evidenced by large number of pachytene spermatocytes and appearance of round spermatids. The present results show that LH-free recombinant FSH, like purified pituitary FSH, is capable of increasing the LH receptor content and steroidogenic responsiveness of Leydig cells through paracrine mechanisms together with a stimulatory effect on spermatogenesis. These observations suggest that prepubertal elevation of FSH secretion may be important for increasing Leydig cell steroidogenic capacity and spermatogenic progression.
尽管早期报告显示促卵泡激素（FSH）对睾丸间质细胞功能有刺激作用，但由于缺乏不含促黄体生成素（LH）污染的FSH制剂，仍存在争议。重组人FSH制剂的近期可得性使得重新研究这个问题成为可能。将未成熟雄性大鼠进行垂体切除（手术时21 - 22日龄），并植入每天释放8国际单位重组FSH或18国际单位纯化人垂体FSH（hpFSH）的渗透微型泵，而对照动物仅接受载体。治疗7天后，重组FSH和hpFSH治疗的动物睾丸重量分别增加至对照动物的2.3倍和2.5倍。对用重组FSH或hpFSH治疗的大鼠睾丸中睾丸间质细胞的类固醇生成能力分析还显示，与对照相比，体外雄激素生成分别增加了2.9倍和3.8倍。在这些大鼠中，重组FSH和hpFSH分别使睾丸匀浆中的LH受体数量增加了50%和70%。LH受体数量的增加与LH受体mRNA水平的增加相关。在垂体切除的对照大鼠中，小的生精小管含有精原细胞和偶线期/早粗线期精母细胞。相反，用任何一种FSH制剂治疗都增强了减数分裂的进程，大量粗线期精母细胞和圆形精子细胞的出现证明了这一点。目前的结果表明，不含LH的重组FSH与纯化的垂体FSH一样，能够通过旁分泌机制增加睾丸间质细胞的LH受体含量和类固醇生成反应性，同时对精子发生有刺激作用。这些观察结果表明，青春期前FSH分泌的升高对于增加睾丸间质细胞类固醇生成能力和精子发生进程可能很重要。
