褪黑素膜受体在泌乳期奶山羊乳腺的表达及褪黑素对乳腺β-酪蛋白表达的影响

Expression of Melatonin Membrane Receptors in the Mammary Gland of Lactating Dairy Goats and the Effect of Melatonin on Mammary β-casein Expression

此试验旨在研究褪黑素膜受体(Melatonin membrane receptors,MT)在奶山羊乳腺中的分布和表达及褪黑素对奶山羊乳腺β-酪蛋白(β-casein)表达的调节作用。以泌乳期奶山羊为研究对象,采用Real-time PCR和免疫组织化学染色方法检测MT1和MT2在泌乳期不同阶段奶山羊乳腺中的表达和分布;褪黑素处理体外培养的泌乳期乳腺组织,Real-time PCR方法检测其β-酪蛋白mRNA的表达情况。结果发现:(1)MT1和MT2 mRNA在泌乳期奶山羊乳腺都有表达,并具有相同的表达趋势,泌乳高峰期(泌乳期60 d)显著高于泌乳上升期(泌乳期30 d)和泌乳下降期(泌乳期120 d)(P<0.05);(2)MT1和MT2主要定位于乳腺上皮细胞,泌乳高峰期为强阳性,泌乳上升期和下降期阳性反应较弱;(3)褪黑素处理能显著下调乳腺组织β-酪蛋白mRNA的表达(P<0.05)。结果表明,褪黑素能直接作用于乳腺,调节泌乳期奶山羊泌乳活动。

To explore the expression of Melatonin membrane receptors(MT1 and MT2)and the direct role of melatonin in the regulation ofβ-casein expression in mammary glands of lactating goat,the lactating dairy goat was used as the study object.The expression of MT1 and MT2 in the mammary glands of goats at different stages of lactation was determined using Real-time PCR and Immunohistochemistry.The cultured lactation mammary tissues by melatonin in vitro was treated,the expression ofβ-casein mRNA was determined using Real-time PCR.Results showed that:the similar trends of MT1 and MT2 mRNA expression were noted during lactation,with higher level in the peak stage(days 60)of lactation,and lower levels in the ascending stage(days 30)and the descending stage(days 120)of lactation(P<0.05).MT1 and MT2 were predominantly localized in the ductal mammary epithelial cells at various stages of lactation.Strong MT1 and MT2 immunoreactive cells were detected in the mammary glands of the peak stage goats.Weak MT1 and MT2 immunoreactive were observed in the epithelial cells of in the mammary tissues of the ascending and the descending stage goats(P<0.05).Melatonin abated the expression ofβ-casein mRNA in cultured mammary tissues(P<0.05).The results indicated the direct action of melatonin in the regulation of mammary function in lactating dairy goats.