卵黄蛋白原在剑尾鱼体内不同组织的分布及雌激素作用对其表达的影响

Vitellogenin in Xiphophorus helleri: distribution and expression under 17β-estradiol exposure

为研究卵黄蛋白原(Vitellogenin,Vg)在剑尾鱼(Xiphophorus helleri)不同组织器官的表达情况,以及了解雌激素对不同组织中Vg表达的诱导作用,将成年雌、雄剑尾鱼及幼鱼暴露于50μg/L的17β-雌二醇(E2)溶液中20d,未暴露的剑尾鱼作对照,采用免疫组化法对各处理组剑尾鱼进行Vg的组织定位研究。结果表明,剑尾鱼Vg主要分布于成熟雌鱼的肝脏、脾脏和肠的血管、淋巴管,在正常幼鱼及雄鱼的以上各组织中均不表达。17β-雌二醇暴露下,剑尾鱼雌、雄成鱼和幼鱼的肝脏以及肾、脾、肠等组织的血管及淋巴管均呈Vg阳性。但Vg颗粒只在肝实质细胞中观察到,在其他组织中如脾脏、肠固有结缔组织等,Vg颗粒仅出现于血管,在细胞内未观察到。以上结果表明,剑尾鱼Vg在肝细胞中合成,通过血液循环到达其他组织;雌激素可诱导雌、雄剑尾鱼及幼鱼肝组织中Vg的表达。剑尾鱼幼鱼及雄鱼Vg的非正常表达可应用于环境雌激素效应评价。

Vitellogenin（Vg） plays an important role in development and reproduction of fish. In order to study the expression of Vg in different organs and tissues of swordtail fish（ Xiphophorus helleri） and to study the induction effect of estrogen on Vg in swordtail fish, immunohistochemistry method was used to investigate the Vg histolocalization in major organs and tissues of sword fish. Mature female and male swordtail fish and juveniles fish were exposed to 50 μg/L 17β-estradiol solution for 20 d. Then liver, spleen, kidney, intestine, brain and muscle of mature fish were sampled and fixed and juvenile fish were wholly fixed. Swordtail fish cultured in natural conditions were set as control. The results showed that Vg mainly distributed in liver, spleen and intestinal connective tissue proper of the mature female fish and could not be observed in the above tissues of male and juvenile fish in normal conditions. Liver, kidney, spleen intestine connective tissue proper of female, male and juvenile swordtail fish all presented positive responses after they were exposed in 17β-estradiol （E2）. Vg particles were only observed in hepatic parenchymal ceils, blood vessels of spleen, intestine connective tissue proper and other organs and tissues, but could not be observed in cells of these organs and tissues except liver. It can be concluded that Vg is synthesized in liver cells of swordtail fish, and reaches other tissues with blood stream and that estrogen can induce the expression of Vg in liver of male and female immature swordtail fish and juvenile fish. The abnormal expression of Vg in juvenile and male swordtail fish can be applied for environmental assessment of estrogen effects. [Journal of Fishery Sciences of China, 2009,16 （5）： 705-711]