Woad K J, Baxter G, Hogg C O, Bramley T A, Webb R, Armstrong D G
Division of Integrative Biology, Roslin Institute, Roslin, Midlothian, Edinburgh EH25 9PS, UK.
J Reprod Fertil. 2000 Nov;120(2):293-302.
Previous studies have implicated insulin-like growth factors I and II (IGF-I and -II), in the regulation of ovarian function. The present study investigated the localization of mRNA encoding IGF-I and -II and the type 1 IGF receptor using in situ hybridization to determine further the roles of the IGFs within the bovine corpus luteum at precise stages of the oestrous cycle. Luteal expression of mRNA encoding IGF-I and -II and the type 1 IGF receptor was detected throughout the oestrous cycle. The expression of IGF-I mRNAvaried significantly during the oestrous cycle. IGF-I mRNA concentrations were significantly higher on day 15 than on day 10, and IGF-I mRNA in the regressing corpus luteum at 48 h after administration of exogenous prostaglandin was significantly greater than in the early or mid-luteal phase (days 5 and 10). In contrast, there was no significant effect of day of the oestrous cycle on expression of mRNA for IGF-II and the type 1 IGF receptor in the corpus luteum. Expression of IGF-II mRNA was localized to a subset of steroidogenic luteal cells and was also associated with cells of the luteal vasculature. mRNA encoding the type 1 IGF receptor was widely expressed in a pattern indicative of expression in large and small luteal cells. These data demonstrate that the bovine corpus luteum is a site of IGF production and reception throughout the luteal phase. Furthermore, this study highlights the potential of IGF-II in addition to IGF-I in the autocrine and paracrine regulation of luteal function.
以往的研究表明，胰岛素样生长因子I和II（IGF-I和-II）参与卵巢功能的调节。本研究利用原位杂交技术，对编码IGF-I、-II和1型IGF受体的mRNA进行定位，以进一步确定IGF在牛发情周期特定阶段黄体中的作用。在整个发情周期中，均检测到编码IGF-I、-II和1型IGF受体的mRNA在黄体中的表达。发情周期中，IGF-I mRNA的表达有显著变化。IGF-I mRNA浓度在第15天显著高于第10天，在给予外源性前列腺素48小时后，退化黄体中的IGF-I mRNA显著高于黄体早期或中期（第5天和第10天）。相比之下，发情周期的天数对黄体中IGF-II和1型IGF受体mRNA的表达没有显著影响。IGF-II mRNA的表达定位于一部分类固醇生成黄体细胞，也与黄体脉管系统的细胞有关。编码1型IGF受体的mRNA在大、小黄体细胞中广泛表达。这些数据表明，在整个黄体期，牛黄体是IGF产生和接收的场所。此外，本研究强调了IGF-II除了IGF-I之外，在黄体功能自分泌和旁分泌调节中的潜力。
