Zhou Hong, Ge Chunmei, Chen Aqin, Lu Weiqun
National Demonstration Center for Experimental Fisheries Science Education, Shanghai Ocean University, Shanghai, China.
Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources, Ministry of Education, Shanghai Ocean University, Shanghai, China.
Front Physiol. 2019 Aug 13;10:1045. doi: 10.3389/fphys.2019.01045. eCollection 2019.
Urotensin I (UI), a fish corticotropin-releasing hormone (CRH) like peptide, has been found throughout vertebrate species that has great effects on adaptive physiology comprising stress-related responses, and osmotic regulation by binding with CRH type I receptor (CRHR1) and CRH type II receptor (CRHR2) in fish. Dynamic expression and regulation of UI and CRH receptors in the olive flounder ovarian follicle were studied so as to make further efforts to understand the role of UI in the development of teleost ovary. The results showed that stage-specific change in UI mRNA levels in ovarian follicles of olive flounder. UI and CRHR1 mRNA levels were higher in stage III follicles (300∼500 μm diameter) compared to stage II (90∼300 μm diameter) and IV (500∼800 μm diameter) follicles, however, the levels of CRHR2 mRNA were decreased in line with the ovarian development from stage II to stage IV. A strong signal of UI protein was observed in the follicular cells and oocyte in stage III and IV follicles by immunohistochemistry. treatment of olive flounder ovarian follicles with human chorionic gonadotropin (hCG) showed that the mRNA expression of UI increased significantly at low concentration and decreased at high concentration at 6 h, but the CRHR1 and CRHR2 mRNA did not change obviously. In addition, the results of incubation with 17α, 20β-dihydroxy-4-oregnen-3-one (DHP) show that UI and CRHR1 mRNA expression were elevated with increasing concentrations at 9 h. All above results indicated that UI and CRH receptors may have a vital effect on olive flounder ovarian development.
尾加压素I（UI）是一种鱼类促肾上腺皮质激素释放激素（CRH）样肽，在整个脊椎动物物种中都有发现，它通过与鱼类中的I型促肾上腺皮质激素释放激素受体（CRHR1）和II型促肾上腺皮质激素释放激素受体（CRHR2）结合，对包括应激相关反应和渗透调节在内的适应性生理有很大影响。研究了牙鲆卵巢卵泡中UI和CRH受体的动态表达及调控，以便进一步了解UI在硬骨鱼卵巢发育中的作用。结果表明，牙鲆卵巢卵泡中UI mRNA水平存在阶段特异性变化。与II期（直径90∼300μm）和IV期（直径500∼800μm）卵泡相比，III期卵泡（直径300∼500μm）中UI和CRHR1 mRNA水平更高，然而，从II期到IV期，随着卵巢发育，CRHR2 mRNA水平降低。通过免疫组织化学在III期和IV期卵泡的卵泡细胞和卵母细胞中观察到强烈的UI蛋白信号。用人绒毛膜促性腺激素（hCG）处理牙鲆卵巢卵泡表明，在6小时时，低浓度下UI的mRNA表达显著增加，高浓度下降低，但CRHR1和CRHR2 mRNA没有明显变化。此外，用17α，20β - 二羟基 - 4 - 孕烯 - 3 - 酮（DHP）孵育的结果表明，在9小时时，UI和CRHR1 mRNA表达随浓度增加而升高。以上所有结果表明，UI和CRH受体可能对牙鲆卵巢发育有重要影响。
