不同类型日粮对泌乳奶牛乳腺组织胰岛素通路及JAK2-STAT信号通路影响

摘要

研究不同类型日粮对奶牛血清激素、乳腺激素受体及其下游相关基因影响.试验选用10头健康泌乳中期荷斯坦奶牛,随机分成2组,分别饲喂不同类型粗饲料日粮,根据粗饲料来源不同,分为单一秸秆型(CS组)与苜蓿、青贮型(MF组).试验预饲期2周,正饲期4周.于正饲期最后1d清晨采集乳静脉血液以及乳腺组织样本.正饲期最后3d记录产奶量,并按早晚4:6比例采集奶样,使用乳成分分析仪测定乳蛋白.采用ELISA(酶联免疫吸附试验)方法和放射性免疫法(RIA)测定血清胰岛素、瘦素、脂联素、胰岛素样生长因子-1、生长激素、催乳素和雌二醇等激素含量,采用qRT-PCR方法测定乳腺相关激素受体及胰岛素下游通路相关基因mRNA表达丰度.结果表明,MF组奶牛血清中胰岛素和脂联素含量显著高于CS组(P＜o.05),其他激素含量并没有显著差异.MF组奶牛乳腺组织中INSR、PRLR、CSF2RB受体,IRS1、IRS4、S6K、JAK2基因mRNA表达量较CS组显著上调(P＜0.05).结果表明,饲喂苜蓿青贮粗饲料型日粮能提高血清中胰岛素和脂联素浓度,并能激活奶牛乳腺胰岛素信号通路与JAK2-STAT通路中部分重要基因表达,从而提高奶牛对饲料利用、促进脂代谢与蛋白质合成,对提高奶牛乳蛋白产量有重要意义.%To determine the relationship between different dietary and serum hormone secretion level,the mRNA expression of hormone receptors and downstream genes in mammary gland of lactating dairy cows were identified by qRT-PCR.10 lactating Holstein dairy cows were randomly assigned to two treatments:com straw treatment (CS),mixed forage treatment (MF).The whole experiment period was divided into two parts,one part was pre-experiment which lasted 2 weeks and the other part was 4-week formal experiment.INS,LEP,ADPN,IGF-1,GH,PRL and E2 were detected by ELASA or RIA.The mRNA abundance of hormone receptors and downstream genes of insulin signaling pathway in mammary gland were assessed by RT-PCR.Results showed that compared with CS group,serum insulin and adiponectin were elevated significantly in MF groups (P＜0.05) while other hormones detected had not significant difference between two groups.The qRT-PCR results revealed that INSR,PRLR,CSF2RB,IRS1,IRS4,S6K and JAK2 had higher abundance in mammary gland in MF group than in CS group (P＜0.05).Different dietary could chang the serum insulin and adiponectin content,mRNA expression of related genes and ultimately affect the expression of gene products.