White S S, Ojeda S R
Endocrinology. 1981 Jul;109(1):152-61. doi: 10.1210/endo-109-1-152.
Ovarian hCG and FSH receptor content was measured at different postnatal ages (days 4-32), at 4-day intervals, and expressed as counts per min 125I-labeled hormone bound/micrograms DNA. Specific FSH binding was minimal at day 4 and increased to a maximum at day 28, with the greatest rate of increase between day 4 and 16. hCG receptor content increased 6-fold between day 4 and 32, but contrasting with FSH, its greatest rate of increase occurred between day 16 and 28. The effectiveness of in vivo treatment with LH in inducing ovarian ornithine decarboxylase (ODC) activity, measured in 20,000 X g supernatants by the in vitro formation of 14CO2 from labeled ornithine, increased significantly during prepubertal development (days 21-33), paralleling the changes in hCG receptors. Ovarian hCG and FSH receptor content was also measured during the time of puberty. Specific hCG binding increased from anestrus (juvenile 32-day-old animals) to 1300 h of the first proestrus. The levels declined significantly by 1600 h of first proestrus and reached minimal values by the morning of estrus. Specific FSH binding also increased from anestrus to first proestrus, but to a much lesser degree, the levels showing only minor fluctuations during the rest of the cycle. hCG receptors measured in granulosa cells during puberty increased to an even greater extent than in the whole ovary; binding exhibited an 8-fold increase from anestrus to 1300 h of first proestrus and then declined to much lower values on estrus and the first diestrus. The capacity of LH to induce ovarian ODC activity increased markedly between anestrus and first proestrus, declining thereafter, and again paralleled the changes in LH receptor content. Evaluation of the kinetics of binding of hCG and FSH with their respective receptors in ovaries of 28-day-old rats revealed that the binding of hCG reached equilibrium within 4-8 h, whereas the binding of FSH attained equilibrium between 12-24 h. In both cases, however, the labeled hormones were clearly dissociable from their respective receptors by addition of an excess of unlabeled hormone. Moreover, although the ovarian receptor content of both hCG and FSH increased during prepubertal development, the equilibrium association constant of either hormone with its receptor remained unchanged. The results suggest that the infantile increase in FSH receptors may be induced by the high serum FSH levels present at that age and that, as shown by others in hypophysectomized rats, the subsequent increase in hCG receptors is, at least in part, an FSH-dependent phenomenon. The parallel changes in hCG receptors and LH-induced ODC activity during pre- and peripubertal development strongly suggest that an increase in LH binding capacity plays a fundamental role in the process of ovarian growth. It is also suggested that the changes in the steroidogenic ovarian response to hCG previously observed in peripubertal rats are, at least in part, determined by changes in ovarian LH receptor content.
在出生后的不同年龄阶段（第4 - 32天），每隔4天测量卵巢中促性腺激素释放激素（hCG）和促卵泡生成素（FSH）受体的含量，并以每分钟125I标记激素结合量/微克DNA表示。特异性FSH结合在第4天最少，在第28天增加到最大值，在第4天到第16天之间增加速率最大。hCG受体含量在第4天到第32天之间增加了6倍，但与FSH不同的是，其最大增加速率出现在第16天到第28天之间。通过体外从标记的鸟氨酸形成14CO2来测量，在20,000×g上清液中，促黄体生成素（LH）体内治疗诱导卵巢鸟氨酸脱羧酶（ODC）活性的效果在青春期前发育阶段（第21 - 33天）显著增加，与hCG受体的变化平行。在青春期期间也测量了卵巢hCG和FSH受体含量。特异性hCG结合从乏情期（32日龄幼年动物）增加到首次发情前期的1300小时。到首次发情前期的1600小时，水平显著下降，到发情期早晨达到最小值。特异性FSH结合也从乏情期增加到首次发情前期，但程度要小得多，在周期的其余时间水平仅显示轻微波动。青春期期间在颗粒细胞中测量的hCG受体增加的程度甚至比整个卵巢更大；结合从乏情期到首次发情前期的1300小时增加了8倍，然后在发情期和第一个间情期下降到低得多的值。LH诱导卵巢ODC活性的能力在乏情期和首次发情前期之间显著增加，此后下降，并且再次与LH受体含量的变化平行。对28日龄大鼠卵巢中hCG和FSH与其各自受体结合动力学的评估表明，hCG的结合在4 - 8小时内达到平衡，而FSH的结合在12 - 24小时之间达到平衡。然而，在这两种情况下，通过添加过量的未标记激素，标记激素都能明显地从其各自受体上解离。此外，尽管hCG和FSH的卵巢受体含量在青春期前发育期间都增加了，但任何一种激素与其受体的平衡结合常数保持不变。结果表明，婴儿期FSH受体的增加可能是由该年龄时高血清FSH水平诱导的，并且如其他人在垂体切除的大鼠中所示，随后hCG受体的增加至少部分是一种FSH依赖性现象。青春期前和青春期期间hCG受体和LH诱导的ODC活性的平行变化强烈表明，LH结合能力的增加在卵巢生长过程中起基本作用。还表明，先前在青春期大鼠中观察到的卵巢对hCG的类固醇生成反应的变化至少部分是由卵巢LH受体含量的变化决定的。
