Ying S Y, Becker A, Swanson G, Tan P, Ling N, Esch F, Ueno N, Shimasaki S, Guillemin R
Salk Institute, Laboratories for Neuroendocrinology, La Jolla, CA 92037.
Biochem Biophys Res Commun. 1987 Nov 30;149(1):133-9. doi: 10.1016/0006-291x(87)91614-7.
Two forms of purified follistatin, a single-chain polypeptide of mol wt 35,000 (35 Kd) protein, and a related molecule of mol wt 32,000 (32 Kd), which differs from the 35 Kd form in glycosylation or carboxyl terminal truncation, specifically inhibit the release of immunoreactive FSH by primary cultures of rat pituitary cells. Both forms of follistatin and inhibin-A give similar dose-response curves, with identical slopes and maximal effects, suggesting that they may all act through the same mechanism on the pituitary cells. The median effective dose (ED50) of each of the follistatins is 6.2-7.3 ng/ml (1.8 x 10(-10) M), which corresponds to approximately 1/3 of the potency of inhibin. The effect of 35 Kd or 32 Kd follistatin is highly specific for suppressing the release of immunoreactive FSH since there is no demonstrable concomitant effect on the secretion of other pituitary hormones. The effect of follistatins, like that of inhibins, is different from that of the hypothalamic hypophysiotropic factors, requiring greater than or equal to 18 h of incubation in a pituitary monolayer culture system to demonstrate. Coincubation of inhibin and follistatin shows an additive effect in the suppression of FSH release. Pituitary cells exposed to follistatin have significantly less depletion of intracellular FSH (0.01) than those treated with inhibin, indicating that follistatin may act primarily on the suppression of FSH release rather than on both release and synthesis of FSH, as is the case with inhibin.
纯化的卵泡抑素存在两种形式，一种是分子量为35,000（35 Kd）的单链多肽蛋白，另一种是分子量为32,000（32 Kd）的相关分子，后者在糖基化或羧基末端截短方面与35 Kd形式不同，它们能特异性抑制大鼠垂体细胞原代培养物中免疫反应性促卵泡生成素（FSH）的释放。两种形式的卵泡抑素和抑制素A给出相似的剂量反应曲线，斜率和最大效应相同，这表明它们可能都通过相同的机制作用于垂体细胞。每种卵泡抑素的半数有效剂量（ED50）为6.2 - 7.3 ng/ml（1.8×10⁻¹⁰ M），约相当于抑制素效力的1/3。35 Kd或32 Kd卵泡抑素的作用对抑制免疫反应性FSH的释放具有高度特异性，因为对其他垂体激素的分泌没有可证实的伴随作用。卵泡抑素的作用与抑制素类似，不同于下丘脑促垂体因子的作用，在垂体单层培养系统中需要孵育大于或等于18小时才能显现。抑制素与卵泡抑素共同孵育显示在抑制FSH释放方面有相加作用。暴露于卵泡抑素的垂体细胞内FSH的消耗明显少于用抑制素处理的细胞（P<0.01），这表明卵泡抑素可能主要作用于抑制FSH的释放，而不像抑制素那样同时作用于FSH的释放和合成。
