Sarkar Shrabanti, Bhattacharya Debapriya, Juin Subir Kumar, Nath Panchanan
Department of Zoology, Visva-Bharati University, Santiniketan, 731235, West Bengal, India.
Fish Physiol Biochem. 2014 Dec;40(6):1849-61. doi: 10.1007/s10695-014-9973-0. Epub 2014 Aug 22.
The biological activities of catfish LH-like (semi-purified: s200a and purified Qa) and FSH-like (semi-purified: s200b and purified: Qb) were compared in intact and hypophysectomized female catfish, Clarias batrachus, during preparatory and the pre-spawning periods on vitellogenesis and ovarian maintenance, as well as in vitro final maturation of oocytes, germinal vesicle breakdown (GVBD). During preparatory period, in intact catfish, semi-purified FSH-like induced complete vitellogenesis through the production of estradiol-17β (E2) and vitellogenin (Vg) accompanied by the formation of SIII yolky oocytes. On the other hand, semi-purified LH-like had induced the formation of only SII (characterized by the appearance of cortical alveoli in cytoplasm) oocytes, which indicates the initiation of vitellogenesis. In hypophysectomized female catfish, purified LH-like but not FSH-like induced the formation of SII oocytes in the ovaries. Treatment with semi-purified LH- and FSH-like at the dose level of 5 µg/fish/day for 7 days significantly maintained the yolky oocytes in gravid catfish after hypophysectomy with a significant reduction in plasma Vg, but not E2 levels, indicating some unknown GtH-induced factor doing the job. In in vitro oocytes culture, both LH- and FSH-like induced GVBD, but the response was significantly more with LH-like than FSH-like. All these findings revealed that both LH-like and FSH-like have overlapping physiological functions, but their responses differ depending on the physiological status of the catfish.
在准备期和产卵前期，对完整及垂体切除的雌性胡子鲶（Clarias batrachus）进行研究，比较鲶鱼促黄体生成素样物质（半纯化：s200a和纯化：Qa）和促卵泡激素样物质（半纯化：s200b和纯化：Qb）对卵黄发生、卵巢维持以及卵母细胞体外最终成熟（生发泡破裂，GVBD）的生物学活性。在准备期，对于完整的鲶鱼，半纯化的促卵泡激素样物质通过产生雌二醇-17β（E2）和卵黄蛋白原（Vg）诱导完全卵黄发生，并伴随着III期卵黄卵母细胞的形成。另一方面，半纯化的促黄体生成素样物质仅诱导形成II期卵母细胞（其特征为细胞质中出现皮质泡），这表明卵黄发生的起始。在垂体切除的雌性鲶鱼中，纯化的促黄体生成素样物质而非促卵泡激素样物质诱导卵巢中II期卵母细胞的形成。以5 μg/鱼/天的剂量水平用半纯化的促黄体生成素样物质和促卵泡激素样物质处理7天，显著维持了垂体切除后的怀卵鲶鱼中的卵黄卵母细胞，血浆Vg水平显著降低，但E2水平未降低，表明有一些未知的促性腺激素诱导因子在起作用。在体外卵母细胞培养中，促黄体生成素样物质和促卵泡激素样物质均诱导GVBD，但促黄体生成素样物质引起的反应明显比促卵泡激素样物质更强烈。所有这些发现表明，促黄体生成素样物质和促卵泡激素样物质具有重叠的生理功能，但它们的反应因鲶鱼的生理状态而异。
