藏鸡和肉鸡种蛋皮质酮沉积与胚胎皮质酮代谢酶表达的差异分析

Comparison analysis of corticosterone deposition in fertilized eggs and embryonic expression of corticosterone metabolic enzymes between Tibetan chickens and broiler chickens

[目的]糖皮质激素(GC)对禽类的胚胎发育至关重要,其生物活性主要受细胞内的糖皮质激素代谢酶的调节。本研究比较了藏鸡和肉鸡种蛋内的皮质酮沉积水平以及胚胎卵黄膜、尿囊膜的皮质酮代谢酶11β-羟基类固醇脱氢酶1(11β-HSD1)、11β-羟基类固醇脱氢酶2(11β-HSD2)和20-羟基类固醇脱氢酶(20-HSD)的表达水平差异。[方法]采用酶联免疫方法检测藏鸡和肉鸡种蛋蛋黄、蛋清内的皮质酮含量,用荧光定量PCR检测14胚龄藏鸡和肉鸡鸡胚卵黄膜、尿囊膜11β-HSD1、11β-HSD2、20-HSD基因的表达情况。[结果]藏鸡蛋蛋黄内皮质酮含量极显著低于肉鸡蛋黄内含量(P<0.01),而两者间蛋清内皮质酮含量没有显著差异(P>0.05)。14胚龄藏鸡卵黄膜11β-HSD2、20-HSD mRNA表达量显著或极显著低于肉鸡(P<0.05或P<0.01);藏鸡鸡胚尿囊膜11β-HSD1、11β-HSD2、20-HSD mRNA表达水平显著或极显著高于肉鸡(P<0.05或P<0.01)。除了藏鸡鸡胚20-HSD基因,同一品种的皮质酮代谢酶基因在卵黄膜上的表达量都高于尿囊膜内含量。[结论]藏鸡和肉鸡种蛋皮质酮沉积及卵黄膜、尿囊膜的皮质酮代谢酶的表达差异在一定程度上可解释品种间表现性状差异的原因。

[Objectives]Glucocorticoids（GC） are vital for embryonic development in avians and their bioactivity is regulated by the intracellular metabolism enzymes involving 11β-hydroxysteroid dehydrogenases 1（11β-HSD1）,11β-hydroxysteroid dehydrogenases 2（11β-HSD2） and 20-hydroxysteroid dehydrogenase（20-HSD）.Here we compared corticosterone deposition in fertilized eggs and embryonic expression of corticosterone metabolic enzymes in yolk sac and chorioallantoic membrene（CAM） between Tibetan chickens and broiler chickens.[Methods]EIA（enzyme-linked immunoassay） kit was used to detect yolk and albumen corticosterone contents in fertilized eggs between Tibetan chickens and broiler chickens.Real-Time PCR was implyed to examine expression levels of 11β-HSD1,11β-HSD2 and 20-HSD mRNA in yolk sac,CAM of Tibetan chickens and broiler chickens on embryonic day of 14（E14）.[Results]The results indicated that fertilized eggs of Tibetan chickens contained significanntly lower（P〈0.01） corticosterone in the yolk compared with that of broiler chickens.The corticosterone contents in albumen had no singnificant difference between the two breeds（P〉0.05）.Yolk sac mRNA expression levels of 11β-HSD2 and 20-HSD in Tibetan chickens were obviously lower than those of broiler chickens on embryonic day of 14（P〈0.05 or P〈0.01）.In the CAM,expression of 11β-HSD1,11β-HSD2 and 20-HSD mRNA in Tibetan chickens was higher enough to be significant than that of broiler chickens at E14.Morever,we found that expression of corticosterone metabolic enzymes in yolk sac was higher than that in CAM except 20-HSD mRNA in Tibetan chickens embryos.[Conclusions]Our study provided the first-hand data that egg deposition of corticosterone,as well as placenta expression of glucocorticoid metabolic enzymes,differs between Tibetan and broiler chickens,which may account for the breed phenotypic expression disparities to some extent.