Mishra A, Joy K P
Department of Zoology, Banaras Hindu University, Varanasi-221005, India.
J Endocrinol. 2006 May;189(2):341-53. doi: 10.1677/joe.1.06686.
An HPLC method was used to tentatively identify progesterone (P4) and its metabolites (17-hydroxyprogesterone (17-P4) and 17,20beta-dihydroxy-4-pregnen-3-one (17,20beta-P)), corticosteroids (cortisol and corticosterone) and testosterone in ovary/follicular preparations of the catfish Heteropneustes fossilis associated with in vivo or in vitro oocyte maturation/ovulation. A single i.p. injection of human chorionic gonadotrophin (100 IU/fish, sampled at 0, 8 and 16 h) induced oocyte maturation and ovulation, which coincided with significant and progressive increases in 17,20beta-P, and P4 and 17-P4, the precursors of the former. Both cortisol and corticosterone also increased significantly. Conversely, testosterone decreased significantly and progressively over time. Under in vitro conditions, incubation of post-vitellogenic (intact) follicles or follicular envelope (layer) with 2-hydroxyoestradiol (2-OHE2, 5 microM for 0, 6 and 24 h) elicited a sharp significant increase in 17,20beta-P, the increase being higher in the follicular envelope incubate. P4 and 17-P4 also registered significant increases over the time with the peak values at 24 h. Cortisol and corticosterone increased significantly in the intact follicle, but not in the follicular envelope incubate. Testosterone decreased significantly in the intact follicle, but increased significantly (24 h) in the follicular envelope incubate. Coincident with these changes, the percentage of germinal vesicle breakdown (GVBD) increased over the time in the intact follicle incubate (48.9% at 6 h and 79.8% at 24 h). Denuded oocytes on incubation with 2-OHE2 (5 microM) did not produce any significant change in the percentage of GVBD or in the steroid profile. While corticosterone and 17,20beta-P were undetected, P4, 17-P4, cortisol and testosterone were detected in low amounts. The results show that the 2-OHE2-induced GVBD response seems to be mediated through the production of 17,20beta-P and corticosteroids. It is suggested that hydroxyoestrogens seem to be a component in the gonadotrophin cascade of regulation of oocyte maturation/ovulation in the catfish.
采用高效液相色谱法（HPLC）初步鉴定鲶鱼（Heteropneustes fossilis）卵巢/卵泡制剂中与体内或体外卵母细胞成熟/排卵相关的孕酮（P4）及其代谢产物（17-羟孕酮（17-P4）和17,20β-二羟基-4-孕烯-3-酮（17,20β-P））、皮质类固醇（皮质醇和皮质酮）以及睾酮。单次腹腔注射人绒毛膜促性腺激素（100 IU/鱼，在0、8和16小时取样）可诱导卵母细胞成熟和排卵，这与17,20β-P以及P4和17-P4（前者的前体）显著且逐渐增加相吻合。皮质醇和皮质酮也显著增加。相反，睾酮随时间显著且逐渐下降。在体外条件下，将卵黄生成后期（完整）卵泡或卵泡膜（层）与2-羟基雌二醇（2-OHE2，5 microM，处理0、6和24小时）一起孵育，可使17,20β-P急剧显著增加，在卵泡膜孵育物中的增加幅度更高。P4和17-P4也随时间显著增加，在24小时达到峰值。皮质醇和皮质酮在完整卵泡中显著增加，但在卵泡膜孵育物中未增加。睾酮在完整卵泡中显著下降，但在卵泡膜孵育物中显著增加（24小时）。与这些变化一致，完整卵泡孵育物中核泡破裂（GVBD）的百分比随时间增加（6小时时为48.9%，24小时时为79.8%）。用2-OHE2（5 microM）孵育去卵丘卵母细胞，GVBD百分比或类固醇谱未产生任何显著变化。虽然未检测到皮质酮和17,20β-P，但检测到少量的P4、17-P4、皮质醇和睾酮。结果表明，2-OHE2诱导的GVBD反应似乎是通过17,20β-P和皮质类固醇的产生介导的。提示羟基雌激素似乎是鲶鱼卵母细胞成熟/排卵调节的促性腺激素级联反应的一个组成部分。
