Kamei Hiroyasu, Kaneko Toyoji, Aida Katsumi
Department of Aquatic Bioscience, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo, Tokyo 113-8657, Japan.
Gen Comp Endocrinol. 2006 Apr;146(2):83-90. doi: 10.1016/j.ygcen.2005.09.019. Epub 2005 Nov 17.
To clarify the physiological functions of follicle-stimulating hormone (FSH) during oogenesis in Japanese eel, Anguilla japonica, the steroidogenic activities of recombinant Japanese eel FSH (rjeFSH) were assessed in the eel ovary. Female eel were injected with salmon pituitary homogenate to enhance the ovarian development, and the ovaries at different developmental stages were subjected to steroidogenic bioassay. These ovaries could be classified into three types according to oocyte growth and development of ovarian follicular cells. The type-A ovary possessed poorly developed follicular cells around pre- or early vitellogenic oocytes, and rjeFSH did not induce sex steroid secretion. Testosterone (T) secretion was stimulated by rjeFSH in the type-B ovary with developed theca cells and undeveloped granulosa cells around early to mid-vitellogenic oocytes, whereas estradiol-17beta (E2) secretion was not enhanced. The rjeFSH stimulated both T and E2 secretion in a dose-dependent manner from the type-C ovary with fully developed theca and granulosa cells around mid-vitellogenic oocytes. Salmon GTH fraction (sGTH) and a membrane permeable cAMP analogue, 8-bromo-cAMP (8-Br-cAMP) also enhanced T and E2 secretion from the type-C ovary. Human chorionic gonadotropin (hCG) similarly enhanced T secretion, but failed to stimulate E2 secretion from the type-C ovary, suggesting different effects on steroidogenic activities between eel FSH and hCG in eel ovary. There was a positive correlation between the oocyte diameter and E2 secretion from eel ovaries stimulated by rjeFSH. These results suggest that aromatase activity is accelerated by eel FSH in the granulosa cells, which develop following theca cell development in this species.
为阐明促卵泡激素（FSH）在日本鳗鲡卵子发生过程中的生理功能，对重组日本鳗鲡FSH（rjeFSH）在鳗鲡卵巢中的类固醇生成活性进行了评估。给雌性鳗鲡注射鲑鱼垂体匀浆以促进卵巢发育，并对不同发育阶段的卵巢进行类固醇生成生物测定。根据卵母细胞生长和卵巢滤泡细胞的发育情况，这些卵巢可分为三种类型。A型卵巢在卵黄发生前期或早期卵母细胞周围的滤泡细胞发育不良，rjeFSH不会诱导性类固醇分泌。在B型卵巢中，rjeFSH刺激了睾酮（T）的分泌，该卵巢在卵黄发生早期至中期卵母细胞周围有发育的卵泡膜细胞和未发育的颗粒细胞，而雌二醇-17β（E2）的分泌并未增强。rjeFSH以剂量依赖的方式刺激C型卵巢分泌T和E2，该卵巢在卵黄发生中期卵母细胞周围有完全发育的卵泡膜细胞和颗粒细胞。鲑鱼促性腺激素组分（sGTH）和一种膜通透性cAMP类似物8-溴-cAMP（8-Br-cAMP）也增强了C型卵巢中T和E2的分泌。人绒毛膜促性腺激素（hCG）同样增强了T的分泌，但未能刺激C型卵巢中E2的分泌，这表明鳗鲡FSH和hCG对鳗鲡卵巢类固醇生成活性的影响不同。rjeFSH刺激的鳗鲡卵巢中卵母细胞直径与E2分泌之间存在正相关。这些结果表明，在该物种中，随着卵泡膜细胞的发育，鳗鲡FSH会加速颗粒细胞中的芳香化酶活性。
