雌二醇对中间球海胆生长、性腺发育及胆固醇代谢的影响

Effects of 17β-estradiol on growth,gonadal development and cholesterol metabolism in sea urchin Strongylocentrotus intermedius

为探讨雌二醇(estradiol)对体质量为(13.58±0.79)g的中间球海胆Strongylocentrotus intermedius性腺发育的调控机制,在室内水槽(200 L)中进行为期60 d的注射试验。试验分对照组、雌二醇(5μg/m L)注射组和他莫昔芬(tamoxifen)(25μg/m L)注射组,每3 d注射1次,并于第30天和第60天时两次取样测定海胆增重率(WGR)、性腺指数(GSI)、性类固醇激素含量和胆固醇合成相关基因的表达量。结果表明:注射雌二醇或他莫昔芬并未显著影响海胆的生长速率,却显著影响试验末期海胆的性腺指数,雌二醇组海胆性腺指数显著高于对照组和他莫昔芬组(P<0.05);试验结束时,雌二醇组和他莫昔芬组海胆体腔液中雌二醇含量和性腺中胆固醇含量均显著高于对照组(P<0.05),雌二醇组海胆性腺中雌二醇含量最高,显著高于对照组和他莫昔芬组(P<0.05);雌二醇组海胆性腺和消化道中主要卵黄蛋白(MYP)基因均高于对照组,但均未有显著性差异(P>0.05);雌二醇组和他莫昔芬组海胆性腺和消化道中性类固醇激素合成关键基因CYP17和胆固醇合成关键基因CYP51表达量均显著高于对照组(P<0.05);他莫昔芬组海胆性腺中CYP17和CYP51基因表达量均低于雌二醇组(P>0.05)。研究表明,注射雌二醇显著提高了中间球海胆性腺指数、体内雌二醇含量和雌二醇合成相关基因的表达量,这可能是雌二醇促进海胆性腺发育的调控机制。

Sea urchin Strongylocentrotus intermedius with body weight of（ 13.58±0.79） g reared in a 200 L tank in a laboratory were injected with 17β-estradiol（ 5 μg/m L）,tamoxifen（ inhibitor of estradiol receptor）（ 25 μg/m L）or sunflower oil（ as control group） once every 3 days,and weight gain rate（ WGR）,gonado-somatic index（ GSI）,gonadal hormone content related to development,and expression of cholesterol synthase-related genes were analyzed 30 d and 60 d after administration to investigate the effects of estradiol on growth performance,gonad development and cholesterol metabolism in sea urchin. The results showed that there was no significant difference in weight gain rate among the three treatments（ P〈0.05）. However,statistical significance was detected in GSI among three treatments,with the maximum in the sea urchins injected with 17β-estradiol at the end of the experiment（ P〈0.05）. There were significantly higher estradiol concentration in the coelomic fluid in the sea urchin in the estradiol and tamoxifen groups than that in the control group（ P〈0.05）. The estradiol concentration in the gonad was significantly higher in sea urchin in the estradiol group than that in the control and tamoxifen groups（ P〈0.05）. The higher transcription of major yolk protein（ MYP） in both gonad and digestive tract was observed in the sea urchin injected with 17β-estradiol than that in the other groups（ P〈0.05）. Similarly,there were significantly higher expressions of CYP17 and CYP51 gene in the gonad and digestive tract in the sea urchins injected with estradiol and tamoxifen than that in the control group. It is concluded that estradiol has positively promoting effects on the gonado-somatic index,estradiol concentration and expression of the genes related to estradiol synthesis. The findings could contribute to elucidate the mechanism of estradiol regulating the gonad development of sea urchins.