17-β雌二醇诱导鲻雌性化的机制

The mechanism of estradiol-17 β inducing female sex differientiation in Mugil cephalus

用原位杂交和免疫细胞化学技术,对服用17 β雌二醇实验组和对照组幼年鲻脑各部和性腺进行芳香化酶的定位。结果发现,芳香化酶转录物和特异性蛋白在幼年鲻端脑(嗅球和大脑)、间脑、中脑和小脑是丰富的。在性别未分化时,芳香化酶免疫活性细胞在幼鲻脑各部的分布密度有显著的差异。在嗅球,对照组芳香化酶免疫阳性细胞的分布密度高于实验组,而在间脑、中脑和小脑实验组免疫阳性细胞数量比对照组多1～3倍,特别是下丘脑视前区芳香化酶的免疫阳性细胞数量尤占优势,提示芳香化酶在幼年鲻性分化中可能起关键的作用。另外,在性分化后,芳香化酶免疫活性还定位在卵巢颗粒细胞和精巢间质细胞与足细胞。同时,免疫阳性物质也定位在卵巢和精巢的生殖细胞。这些结果揭示了17 β雌二醇诱发幼鲻雌性化的机制可能是通过芳香化酶的介导,本研究首次提供形态学新的证据。最后,文中还讨论了芳香化酶在鲻性腺发育中可能的生理作用。

In situ hybridization and immunocytochemical techniques for aromatase localization in each region of brain and gonads in the experimental group(treated with 17β -E_2 diet) and control group (without E_2 treatment ) of young grey mullets were carried out. The results show that aromatase transcript and specific protein were abundant in the telencephalon (olfactory bulb and cerebrum),dienecephalon, mesencephalon and cerebelli of young grey mullets. The distributive density of aromatase immunoreactive cells in each region of brain had obvious difference in the sex undifferentiated period between experimental group and control group. In olfactory bulb, the distributive density of aromatase immunoreactive cells in the control group was higher than that in experimental group, but the density of positive cells in the dienecephalon, mesencephalon, and cerebelli in the experimental group were about 1-3 times higher than that in the control group, and the density of aromatase immunoreactive cells showed dominance in the preoptic area of hypothalamus, especially. This suggests that aromatase may play a key role in the sex differentiation of young grey mullets. In addition, after sex differentiation aromatase immunoreactivity was localized in the granular cells of ovary and Leydig cells and Sertoli cells of testis. At the same time, aromatase immunopositive substance also distributed in the germ cells of ovary and testis. These results revealed that the mechanism of 17 β-E_2 inducing feminization may be mediated by aromatase. The study will provide for the first time a new proof. Finally, the physiological role of aromatase in the gonadal development was discussed in the paper.