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

Effect of different dietary on insulin signaling pathway and JAK2STAT signaling pathway of breast tissue in lactating dairy cows

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1 d清晨采集乳静脉血液以及乳腺组织样本。正饲期最后3 d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<0.05),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 dairycows were identified by qRT-PCR. 10 lactating Holstein dairy cows were randomly assigned to two treatments： corn 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, IRSl, 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.