Chourasia T K, Joy K P
Center of Advanced Study, Department of Zoology, Banaras Hindu University, Varanasi 221005, India.
Gen Comp Endocrinol. 2008 Jan 15;155(2):413-21. doi: 10.1016/j.ygcen.2007.07.005. Epub 2007 Aug 3.
Estrogen-2/4-hydroxylase (EH) activity was measured radiometrically in ovaries of catfish injected with hCG intraperitoneally and in postvitellogenic follicles incubated with different concentrations of hCG, catfish (Clarias batrachus) growth hormone (GH), bovine insulin or recombinant human insulin-like growth factor-I (rhIGF-I). The change in enzyme activity was correlated with germinal vesicle breakdown (GVBD), an index of oocyte maturation. A single intraperitoneal injection of hCG (100 IU/fish) stimulated EH activity both at 8 and 16 h prior to stripping of eggs. The activity decreased significantly at 24 h, following ovulation. The follicles incubated with hCG, rhIGF-I, insulin or GH elicited biphasic effects on EH activity. rhIGF-I, insulin and GH increased enzyme activity at the lower or median concentrations. hCG and rhIGF-I stimulated EH activity higher than GH or insulin. All the hormones elicited a dose-dependent increase in GVBD, the effect was greater with rhIGF-I (100 nM) and hCG (5.0 IU/ml). The significance of changes in EH activity (E2 hydroxylation) and GVBD were discussed.
通过放射性测定法，检测了腹腔注射人绒毛膜促性腺激素（hCG）的鲶鱼卵巢以及与不同浓度的hCG、鲶鱼（胡子鲶）生长激素（GH）、牛胰岛素或重组人胰岛素样生长因子-I（rhIGF-I）共同孵育的卵黄生成后期卵泡中的雌激素-2/4-羟化酶（EH）活性。酶活性的变化与生发泡破裂（GVBD）相关，GVBD是卵母细胞成熟的一个指标。单次腹腔注射hCG（100 IU/鱼）在取卵前8小时和16小时均刺激了EH活性。排卵后24小时，该活性显著下降。与hCG、rhIGF-I、胰岛素或GH共同孵育的卵泡对EH活性产生双相作用。rhIGF-I、胰岛素和GH在较低或中等浓度时增加了酶活性。hCG和rhIGF-I刺激EH活性的程度高于GH或胰岛素。所有激素均引起GVBD呈剂量依赖性增加，rhIGF-I（100 nM）和hCG（5.0 IU/ml）的作用更强。讨论了EH活性（E2羟化）和GVBD变化的意义。
