Glass A R, Steinberger A, Swerdloff R, Vigersky R A
Endocrinology. 1982 May;110(5):1542-6. doi: 10.1210/endo-110-5-1542.
Previous studies have shown that weanling male rats fed a low protein diet ad libitum develop hypogonadotropic hypogonadism. Two unusual features of this state were 1) subnormal serum FSH in noncastrate rats but not in castrate rats, suggesting that FSH was being suppressed by a testicular factor, and 2) serum FSH increases after castration that were greater in protein-deficient rats than in controls. In the current study, protein-deficient rats showed FSH hyperresponse to castration, compared to either ad libitum or pair-fed controls, after periods of low protein feeding from 1-8 weeks and periods of castration from 1-8 weeks. FSH hyperresponse to castration was rapidly induced after the start of low protein feeding and was present whether castration was performed before or after low protein feeding was begun. In none of these circumstances did protein-deficient rats show LH hyperresponse to castration. Inhibin production of Sertoli cell cultures prepared from protein-deficient rats was less (P less than 0.02) than in ad libitum or pair-fed controls, suggesting that inhibin overproduction was not the cause of subnormal serum FSH in noncastrate protein-deficient rats. However, castrated rats fed a low protein diet were more sensitive to the negative feedback effects of testosterone on gonadotropin secretion than were ad libitum or pair-fed controls. We conclude that low serum gonadotropins in protein-deficient male rats may be related to hypersensitivity of these animals to the negative feedback effects of testosterone on gonadotropin secretion. In addition, FSH hyperresponse to castration, without corresponding LH hyperresponse, seems to be typical of protein deficiency, suggesting that protein deficiency may be a useful model for exploring the differential control of gonadotropin secretion.
先前的研究表明，随意进食低蛋白饮食的断乳雄性大鼠会发生促性腺激素分泌不足性性腺功能减退。这种状态的两个不寻常特征是：1）未阉割大鼠的血清促卵泡激素（FSH）低于正常水平，而阉割大鼠则不然，这表明FSH受到睾丸因子的抑制；2）阉割后血清FSH升高，蛋白质缺乏的大鼠比对照组更明显。在当前研究中，在1 - 8周进行低蛋白喂养以及1 - 8周进行阉割后，与随意进食或配对喂养的对照组相比，蛋白质缺乏的大鼠表现出对阉割的FSH高反应。开始低蛋白喂养后迅速诱导出对阉割的FSH高反应，无论阉割是在低蛋白喂养开始之前还是之后进行，这种高反应都存在。在所有这些情况下，蛋白质缺乏的大鼠均未表现出对阉割的促黄体生成素（LH）高反应。从蛋白质缺乏的大鼠制备的支持细胞培养物中抑制素的产生比随意进食或配对喂养的对照组少（P小于0.02），这表明抑制素产生过多不是未阉割的蛋白质缺乏大鼠血清FSH低于正常水平的原因。然而，与随意进食或配对喂养的对照组相比，喂食低蛋白饮食的阉割大鼠对睾酮对促性腺激素分泌的负反馈作用更敏感。我们得出结论，蛋白质缺乏的雄性大鼠血清促性腺激素水平低可能与这些动物对睾酮对促性腺激素分泌的负反馈作用过敏有关。此外，对阉割的FSH高反应而无相应的LH高反应似乎是蛋白质缺乏的典型表现，这表明蛋白质缺乏可能是探索促性腺激素分泌差异控制的有用模型。
