Erickson G F, Nakatani A, Ling N, Shimasaki S
Department of Reproductive Medicine, University of California-San Diego, La Jolla 92093-0625.
Endocrinology. 1992 Apr;130(4):1867-78. doi: 10.1210/endo.130.4.1372237.
To investigate the potential role of insulin-like growth factor-binding protein-5 (IGFBP-5) in ovarian physiology, we employed in situ hybridization and Northern analysis to localize IGFBP-5 mRNA in rat ovaries during the estrous cycle. By Northern analysis, the mRNA was abundant at all stages of the cycle. Two species of mRNAs were detected, with sizes of 6.0 and 1.8 kilobases, respectively. The relative amounts of the two transcripts changed throughout the cycle. By in situ hybridization, IGFBP-5 mRNA was expressed in only a few cell types: 1) granulosa cells of some atretic follicles, 2) some secondary interstitial cells, 3) some corpora lutea, and 4) the surface epithelium. The levels of message in both the granulosa and secondary interstitial cells changed over the cycle. At 1000 h on proestrus (before the LH/FSH surge), the message was expressed in only a few follicles. Interestingly, all were small atretic preantral (200-250 microns) follicles. At 2000 h on proestrus (after the LH/FSH surge), the IGFBP-5 mRNA was more abundant; now almost every atretic preantral follicle showed a strong hybridization signal. At 0200 and 1000 h on estrus, the mRNA appeared for the first time in granulosa cells of some atretic antral follicles and in secondary interstitial cells. Hence, virtually all atretic follicles, preantral and antral, now showed IGFBP-5 gene expression. In contrast to that on proestrus and estrus, the hybridization signal on diestrous days 1 and 2 was much less prominent and was found in only a few atretic preantral follicles. Throughout the cycle, IGFBP-5 mRNA was evident in some corpora lutea, but it was not particularly prominent. Abundant IGFBP-5 mRNA was evident in the surface epithelium, and no change was detected over the cycle. Dominant follicles were devoid of IGFBP-5 mRNA. In conclusion, this paper presents the first evidence that the IGFBP-5 gene is expressed in the adult rat ovary. The IGFBP gene is expressed in a cell-specific manner, e.g. in atretic granulosa, secondary interstitial cells, corpora lutea, and the surface epithelium, and the stage of the cycle significantly affected message levels, especially in atretic granulosa and secondary interstitial cells around estrous morning. These findings suggest that IGBP-5 may be an autocrine/paracrine regulator of ovarian physiology, particularly in relation to preantral follicle atresia.
为研究胰岛素样生长因子结合蛋白5（IGFBP - 5）在卵巢生理中的潜在作用，我们采用原位杂交和Northern分析来定位动情周期大鼠卵巢中IGFBP - 5 mRNA。通过Northern分析，该mRNA在动情周期的所有阶段均大量存在。检测到两种mRNA，大小分别为6.0和1.8千碱基。两种转录本的相对含量在整个周期中发生变化。通过原位杂交，IGFBP - 5 mRNA仅在少数细胞类型中表达：1）一些闭锁卵泡的颗粒细胞；2）一些次级间质细胞；3）一些黄体；4）表面上皮。颗粒细胞和次级间质细胞中的mRNA水平在整个周期中发生变化。在发情前期1000 h（LH/FSH峰之前），仅在少数卵泡中表达该信息。有趣的是，所有卵泡均为小的闭锁前卵泡（200 - 250微米）。在发情前期2000 h（LH/FSH峰之后），IGFBP - 5 mRNA更为丰富；此时几乎每个闭锁前卵泡均显示出强烈的杂交信号。在发情期0200和1000 h，mRNA首次出现在一些闭锁卵泡的颗粒细胞和次级间质细胞中。因此，实际上所有闭锁卵泡，包括前卵泡和窦卵泡，现在均显示出IGFBP - 5基因表达。与发情前期和发情期相比，在动情后期第1天和第2天的杂交信号明显较弱，仅在少数闭锁前卵泡中发现。在整个周期中，IGFBP - 5 mRNA在一些黄体中可见，但并不特别显著。表面上皮中IGFBP - 5 mRNA丰富，在整个周期中未检测到变化。优势卵泡缺乏IGFBP - 5 mRNA。总之，本文首次证明IGFBP - 5基因在成年大鼠卵巢中表达。IGFBP基因以细胞特异性方式表达，例如在闭锁颗粒细胞、次级间质细胞、黄体和表面上皮中，并且周期阶段显著影响信息水平，尤其是在发情期早晨前后的闭锁颗粒细胞和次级间质细胞中。这些发现表明IGBP - 5可能是卵巢生理的自分泌/旁分泌调节因子，特别是与前卵泡闭锁有关。
