Evidence that changes in tonic luteinizing hormone secretion determine the growth of preovulatory follicles in the rat.
Evidence that changes in tonic luteinizing hormone secretion determine the growth of preovulatory follicles in the rat.
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有证据表明，强效黄体生成素分泌的变化决定了大鼠排卵前卵泡的生长。
DOI：
10.1210/endo-107-3-641
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发表时间：
1980
期刊：
影响因子：
4.8
通讯作者：
K. Kersey
中科院分区：
文献类型：
--
作者：
J. Richards;J. Jonassen;K. Kersey
通过将植入物插入30日龄大鼠体内维持孕酮的生理浓度（20-100 ng/ml），延迟首次排卵，并在47日龄时停用孕酮，使大鼠的首次排卵同步。抑制排卵涉及对LH和FSH分泌的负反馈调节，对促性腺激素峰的阻断，以及对排卵前卵泡生长的抑制，但对窦卵泡生长无影响。取出植入物导致血清孕酮在0-12 h内从100 ng/ml迅速下降至5 ng/ml。在0-36小时之间，血清LH和FSH浓度逐渐增加，体外培养的单个卵泡在有或没有外源性底物的情况下雌二醇的积累增强，卵泡膜细胞和颗粒细胞中LH（但不是FSH）受体的含量显著逐渐增加。这些事件之后是48 h（第49天1800 h）促性腺激素激增、排卵和黄体化的形态学和生化体征，包括卵泡促性腺激素受体含量和雌二醇蓄积减少，60 h时明显。除基础LH的变化外，这一系列事件在时间和模式上与动情间期第2天孕酮下降和5天周期动情前期排卵后的事件非常相似。虽然不能排除孕酮对卵巢卵泡细胞功能的直接影响，但数据表明，LH（可能还有FSH）的微妙但持续的增加是大鼠动情周期的动情间期和动情前期之间发生的雌二醇和LH结合活性增强卵泡蓄积所必需的。因此，也许一些神秘的内分泌事件之间的动情间期和动情前期可以归因于血清LH的变化已经太小和/或变量为目前的非系列采样方法和RIA可靠地检测。
Physiological concentrations of progesterone (20-100 ng/ml), maintained by the insertion of implants into 30-day-old rats, delayed first ovulation, and withdrawal of progesterone on day 47 of age synchronized first ovulation in rats. Inhibition of ovulation involved negative feedback regulation of tonic LH and FSH secretion, blockage of gonadotropin surges, and suppression of preovulatory, but not antral, follicular growth. Removal of implants resulted in a rapid decline in serum progestrone from 100 to 5 ng/ml within 0-12 h. Between 0-36 h there were progressive increases in serum concentrations of LH and FSH, enhanced accumulation of estradiol by individual follicles incubated in vitro with or without exogenous substrate, and marked progressive increases in the content of LH (but not FSH) receptors in both thecal and granulosa cells. These events were followed by gonadotropin surges at 48 h (1800 h on day 49), ovulation, and morphological and biochemical signs of luteinization, including decreases in follicular gonadotropin receptor content and estradiol accumulation, evident by 60 h. With the exception of changes in basal LH, this sequence of events is remarkably similar in time and pattern to that after the decline of progesterone on diestrous day 2 and ovulation on proestrus of a 5-day cycle. Although a direct effect of progesterone on ovarian follicular cell function cannot be excluded, the data suggest that subtle but sustained increases in LH (and possibly FSH) are required for the enhanced follicular accumulation of estradiol and LH-binding activity occurring between diestrus and proestrus of the rat estrous cycle. Thus, perhaps some of the mystery surrounding the endocrine events between diestrus and proestrus can be ascribed to changes in serum LH that have been too small and/or variable for current nonserial sampling methods and RIAs to detect reliably.