GONADOTROPINS AND ESTRADIOL STIMULATE IMMUNOREACTIVE INSULIN-LIKE GROWTH FACTOR-I PRODUCTION BY PORCINE GRANULOSA-CELLS INVITRO
GONADOTROPINS AND ESTRADIOL STIMULATE IMMUNOREACTIVE INSULIN-LIKE GROWTH FACTOR-I PRODUCTION BY PORCINE GRANULOSA-CELLS INVITRO
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DOI：
10.1210/endo-120-1-198
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发表时间：
1987-01-01
期刊：
影响因子：
4.8
通讯作者：
HAMMOND, JM
中科院分区：
文献类型：
--
作者：
HSU, CJ;HAMMOND, JM
以前的研究已经证实卵巢颗粒细胞是胰岛素样生长因子-I(IGF-I)分泌和作用的场所，这表明这种多肽在卵巢中具有自分泌功能。为了更好地了解这一假定的自分泌系统是如何调节的，以及它与经典的卵巢营养激素FSH、LH和雌二醇(E2)的相互作用，我们研究了这些激素对培养的猪颗粒细胞分泌免疫反应性IGF-I(iIGF-I)的影响。未成熟的颗粒细胞在无血清条件下培养，该条件被优化以允许最大限度地产生iIGF-I和激素反应。用酸性凝胶过滤或反相色谱滤除IGF结合蛋白的影响后进行IIGF-I的测定。由于两种制备法的结果大体相当，大多数样品选择了较多的反相法。放线菌酮几乎消除了培养中可测的IGF-I，这表明所测的多肽是新合成的，培养的颗粒细胞对IGF-I的降解可以忽略不计。因此，培养液水平提供了收集期间细胞分泌的准确指示。在最佳培养条件下，iIGF-I很容易被测量，并且对卵巢营养激素的处理有反应。在这些激素的多次试验中，iIGF-I水平如下：FSH处理，1.58。+-。对照组(n=5)的0.21倍，E_2处理1.26±-。对照组(n=5)的0.12倍，雌二醇加FSH为3.12倍。LH值为对照的0.31倍(n=8)，LH1.33。对照组(n=3)的0.12倍，促黄体生成素加促卵泡刺激素为1.78。为控制值的0.2倍(n=1)。为了评价cAMP在促性腺激素调节系统中的作用，用磷酸二酯酶抑制剂(甲基异丁基黄嘌呤)处理颗粒细胞，使iIGF-I水平为1.61+-。是对照水平的0.7倍。在FSH存在下，表现出进一步的刺激作用(3.76。+-)。对照的0.29倍)。此外，cAMP类似物8-溴-cAMP显著增加iIGF-I水平(6.3+-。对照的0.72倍)。这些数据首次证明，参与卵巢营养调节的主要激素可以刺激性腺分泌iIGF-I。与颗粒细胞的其他促性腺激素依赖功能一样，这种作用似乎是由cAMP介导的，并被E2增强。循环激素和自分泌系统之间的这种界面可以提供一个重要的机制，在局部水平上放大促性腺激素的影响。
Previous studies have established the ovarian granulosa cell as a site of insulin-like growth factor-I (IGF-I) secretion and action, suggesting an autocrine function for this peptide in the ovary. To better understand how this putative autocrine system is regulated and its interface with the classic ovarian trophic hormones FSH, LH, and estradiol (E2), we have studied the effects of these hormones on the secretion of immunoreactive IGF-I (iIGF-I) by cultured porcine granulosa cells. Immature granulosa cells were cultured under serum-free conditions which were optimized to allow maximal iIGF-I production and hormonal responsivity. Measurements of iIGF-I were made after minizing the influence of IGF-binding proteins by either acid gel filtration or reverse phase chromatography. Since the two preparative procedures gave roughly comparable results, the more expeditions reverse phase procedure was chosen for most samples. Cycloheximide virtually eliminated measurable iIGF-I in culture, suggesting that the peptide measured was newly synthesized, and degradation of IGF-I by cultured granulosa cells was negligible. Consequently, the medium levels provided an accurate indication of cellular secretion over the collection period. Under optimal culture conditions, iIGF-I was readily measurable and responsive to treatment with ovarian trophic hormones. The iIGF-I levels in several experiments with these hormones were as follows: FSH treatment, 1.58 .+-. 0.21 times the control value (n = 5 experiments); E2 treatment, 1.26 .+-. 0.12 times the control value (n = 5); E2 plus FSH, 3.12 .times. 0.31 times the control value (n = 8); LH, 1.33 .+-. 0.12 times the control value (n = 3); LH plus FSH,1.78 .+-. 0.2 times the control value (n = 1). To assess the role of cAMP in the mediation of gonadotropin effects in this system, granulosa cells were treated with a phosphodiesterase inhibitor (methylisobutylxanthine), which resulted in iIGF-I levels 1.61 .+-. 0.7 times the control level. In the presence of FSH, a further stimulatory effect was demonstrated (3.76 .+-. 0.29 times control). In addition, the cAMP analog 8-bromo-cAMP dramatically increased iIGF-I levels (6.3 .+-. 0.72 times control). These data provide the first demonstration that gonadal iIGF-I secretion can be stimulated by the principal hormones involved in trophic regulation of the ovary. As with other gonadotropin-dependent functions of granulosa cells, this effect appears to be mediated by cAMP and enhanced by E2. This interface between circulating hormones and autocrine systems could provide an important mechanism to amplify the effects of gonadotropic hormones on a local level.