Department of Obstetrics and Gynecology, Herlev Hospital, Faculty of Health Sciences, University of Copenhagen, Denmark.
Cell Tissue Res. 2012 Dec;350(3):539-48. doi: 10.1007/s00441-012-1489-2. Epub 2012 Sep 1.
Daily oscillations of clock genes have recently been demonstrated in the ovaries of several species. Clock gene knockout or mutant mice demonstrate a variety of reproductive defects. Accumulating evidence suggests that these rhythms act to synchronise the expression of specific ovarian genes to hypothalamo-pituitary signals and that they are regulated by one or both of the gonadotropins. The aim of this study has been to examine the spatio-temporal expression of the clock genes Per1 and Bmal1 during gonadotropin-independent and gonadotropin-dependent follicle development in the rat ovary. We have examined the ovaries of prepubertal rats, of prepubertal rats stimulated with equine chorionic gonadotropin (eCG)/human chorionic gonadotropin (hCG) and of hypophysectomised adult animals. Using quantitative reverse transcription with the polymerase chain reaction, in situ hybridisation histochemistry and immunohistochemistry, we have demonstrated that the expression of the two clock genes is low and arrhythmic in ovarian cells during early gonadotropin-independent follicle development in prepubertal animals and in hypophysectomised animals. We have also demonstrated that the expression of the clock genes becomes rhythmic following eCG stimulation in the theca interna cells and the secondary interstitial cells and that, following additional hCG stimulation, the expression of the clock genes also becomes rhythmic in the granulosa cells of preovulatory follicles. These findings link the initiation of clock gene rhythms in the rat ovary to the luteinising hormone receptor and suggest a functional link to androgen and progesterone production. In hypophysectomised animals, rhythmic clock gene expression is also observed in the corpora lutea and in secondary interstitial cells demonstrating that, in these compartments, entrainment of clock gene rhythms is gonadotropin-independent.
时钟基因的日常波动最近在几种物种的卵巢中得到证实。敲除或突变时钟基因的小鼠表现出多种生殖缺陷。越来越多的证据表明，这些节律作用是将特定卵巢基因的表达同步到下丘脑-垂体信号，并受一种或两种促性腺激素调节。本研究的目的是检查时钟基因 Per1 和 Bmal1 在促性腺激素独立和促性腺激素依赖的卵泡发育过程中的时空表达。我们检查了未成熟大鼠、用马绒毛膜促性腺激素（eCG）/人绒毛膜促性腺激素（hCG）刺激的未成熟大鼠和垂体切除的成年动物的卵巢。通过聚合酶链反应的定量反转录、原位杂交组织化学和免疫组织化学，我们证明了在未成熟动物和垂体切除动物的早期促性腺激素独立卵泡发育过程中，两种时钟基因在卵巢细胞中的表达水平较低且无节律。我们还证明，在 eCG 刺激后，时钟基因在卵巢间质细胞和次级间质细胞中的表达变得有节律，并且在 hCG 刺激后，时钟基因在排卵前卵泡的颗粒细胞中的表达也变得有节律。这些发现将大鼠卵巢中时钟基因节律的启动与黄体生成素受体联系起来，并表明与雄激素和孕激素产生的功能联系。在垂体切除动物中，黄体和次级间质细胞中也观察到节律性时钟基因表达，表明在这些隔室中，时钟基因节律的同步是促性腺激素独立的。
