外源性促性腺激素诱导日本鳗鲡精子发生和成熟的作用机制

用兔抗血清对抗促黄体素生成素受体（LHR）或称绒毛膜促性腺激素受体（CGR）和雄激素受体（AR）进行LHR和AR免疫组织化学定位,以揭示外源性促性腺激素（鲤脑垂体激素和hCG）诱发日本鳗鲡精子发生及其内分泌机制。结果表明,经过注射激素处理后的实验组与注射前的对照组相比较,其精巢发育和精子发生出现十分显著的变化。组织学切片观察显示,激素处理前鳗鲡精巢处于精原细胞增殖期,而两种激素混合注射后第10天,实验组可见精小叶中精原细胞的有丝分裂和初级与次级精母细胞的数量显著的增加。注射后第35天,靠近生殖上皮除有少量精原细胞外,精小叶中有大量初级精母细胞和次级精母细胞和少数精子细胞以及管腔中存在少量精子。在注射后第83天,日本鳗鲡完成了精子发生和精巢发育成熟以及释精。免疫组织化学染色结果进一步揭示,激素处理前,LH受体免疫活性分布在生殖上皮,显示强的免疫阳性反应;激素处理后,LH受体定位在Sertoli细胞和间质细胞以及精原细胞和初级与次级精母细胞的胞膜上,均显示强的免疫阳性反应。激素处理前,雄激素受体定位在生殖上皮和早期生精细胞的胞膜上;激素处理后,AR则定位在这些生精细胞的核或胞质,而精子细胞和精子显示免疫阴性反应。这些结果首次证明了这两种激素诱导鳗鲡精子发生和成熟的作用机制是通过LH受体和雄激素受体的介导。

The action mechanism of exogenous gonadotropin inducing spermatogenesis and maturity of testis in Japanese eel, Anguilla japonica

Immunohistochemical localization of LHR and AR was performed by using rabbit anti serums against leuteinizing hormone receptor (LHR or choriogonadotropin receptor CGR) and androgen receptor (AR). The aim of present study was to reveal the endocrine mechanism of exogenous gonadotropin (CPH and hCG) inducing spermatogenesis in testis of Japanese eel. The results showed that the testis and spermatogenesis in Japanese eel displayed very marked changes after hormone injection. The observation of histological section showed the testis of eel was at the stage of spermatogonia proliferation before hormone treatment, while ten days after the injection of the combination of two gonadotropins, the spermatogonia mitosis and number increase of primary and second spermatocytes in the lobule of testis of male eel were seen. Thirty five days after hormone treatment, a lot of primary and second spermatocytes in the lobule of testis as well as some sperms in the lumen of seminiferous tubule, except a few spermatogonia near reproductive epithelium, could be seen. Eight three days after hormone treatment, the spermatogenesis and the development and maturity as well as spermiation of testis in male eel completed. Immunohistochemical staining results further revealed that LH or CG receptors immunoreactivity was located on the reproductive epithelium showing strong immuno positive reaction before hormone treatment, while LH receptors immunoreactivity was located on the cytomembrane of Sertoli cells, Leydig cell or interstitial cell, spermatogonia, primary and second spermatocytes showing strong immuno positive reaction after hormone treatment. Before hormone treatment, androgen receptors were located on the cytomembrane of spermatogenic cells and reproductive epithelium, while AR were located within nucleus or in cytoplasm of these spermatogenic cells, but spermatids and sperm showed immuno negative reaction. The results demonstrated for the first time that the action mechanism of two hormones inducing spermatogenesis and maturity in eel is mediated by their corresponding receptors. Thus, the present study will provide scientific basis for the dosage and intervallic time of injecting hormones during artificial propagation of eel.