甲状腺功能减退对新生仔鼠心肌肌浆网钙转运蛋白表达的影响  

Alteration of myocardial sarcoplasmic reticulum Ca^(2+) transport protein expression in neonatal hypothyroid rats

作　　者：毛姗姗[1] 赵正言[1] 

机构地区：[1]浙江大学医学院附属儿童医院儿童保健科,浙江杭州310003

出　　处：《中国病理生理杂志》2011年第4期763-768,共6页Chinese Journal of Pathophysiology

基　　金：浙江省教育厅科研资助项目(No.Y201019211)

摘　　要：目的:探讨甲状腺功能减退(甲减)对新生仔鼠心肌肌浆网钙转运蛋白肌浆网Ca^(2+)-ATP酶(SERCA2a)、磷酸受纳蛋白(PLB)mRNA表达以及肌浆网Ca^(2+)-ATP酶活性的影响,并观察左旋甲状腺素(L-T_4)替代治疗后以上指标的改变。方法:SD孕鼠自孕15d起予丙基硫氧嘧啶(PTU)(50mg/d)灌胃至仔鼠出生并持续整个哺乳期,制成围生期甲减模型,并对部分甲减仔鼠自出生当天起每天腹腔注射L-T_4(20μg/kg)。收集甲减、治疗及对照组出生3、5、7日龄的仔鼠心室肌组织(每组10只),应用实时荧光定量PCR方法检测SERCA2a及PLB mRNA含量,并同时采用荧光分光光度计法测定心肌细胞内游离钙(MyoCa^(2+))浓度,无机磷酸根法检测心肌肌浆网钙泵活性。结果:实时荧光定量PCR结果显示甲减组新生仔鼠心肌SERCA2a mRNA水平下降(P<0.05),PLB mRNA水平升高(P<0.01),SERCA2a/PLB下降(P<0.01);L-T_4治疗组仔鼠SERCA2a mRNA水平较甲减组上升(P<0.05),PLB mRNA水平下降(P<0.05),SERCA2a/PLB上升(P<0.01)。心肌细胞内游离钙浓度检测结果显示甲减组心肌细胞MyoCa^(2+)浓度较同日龄对照组升高(P<0.01);L-T_4治疗组仔鼠心肌细胞MyoCa^(2+)浓度低于同日龄甲减组仔鼠(P<0.05)。酶活性检测结果显示甲减组仔鼠肌浆网Ca^(2+)-ATP酶活性低于同日龄对照组(P<0.01);L-T_4治疗组仔鼠肌浆网Ca^(2+)-ATP酶活性较同日龄甲减组仔鼠升高(P<0.05)。结论:甲状腺激素缺乏可使新生大鼠肌浆网Ca^(2+)-ATP酶活性降低,并下调SERCA2a表达,上调PLB表达;肌浆网钙转运蛋白SERCA2a与PLB参与调控围生期甲减诱发的新生仔鼠心功能下降。AIM：To investigate the alteration of sarcoplasmic reticulum（SR）Ca^（2＋）transport proteins including sarcoplasmic reticulum Ca^（2＋）-ATPase 2a（SERCA2a）and phospholamban（PLB）mRNA expression as well as the alteration of myocardial SR Ca^（2＋）-ATPase activity in neonatal hypothyroid rats,and to explore the effect of levothyroxine（L -T_4）substitution therapy on the above indexes.METHODS：Hypothyroidism was induced by the administration of propy-lthiouracil （PTU,50 mg/d）to the pregnant SD rats by gavage beginning on embryonic day 15 and continuing throughout the lactational period.A subgroup of neonatal hypothyroid rats were intraperitoneally injected with L-T_4（20μg/kg BW daily）,starting from the day of birth.Other pregnant SD rats received normal saline instead of PTU.The samples of the rats in all 3 groups were harvested at postnatal day 3,5 and 7（n=10）.After measurement of serum thyroid hormone levels, the hearts were removed and the ventricles were weighed（HW）.The concentration of calcium in ventricular myocardium （ventricular myoCa^（2＋））was detected by fluorospectrophotometry and the activity of SR Ca^（2＋）-ATPase was determined by the inorganic phosphorus method.The mRNA expression of SERCA2a and PLB was also detected by real-time PCR. RESULTS：Neonatal hypothyroid rats had a significant lower level of SERCA2a mRNA（P〈0.05）and a higher level of PLB mRNA（P〈0.01）,and subsequent lower SERCA2a/PLB at each postnatal day（P〈0.01）was observed.Compared with hypothyroid group,the mRNA expression of SERCA2a significantly increased（P〈0.05）and that of PLB significantly decreased（P〈0.05）in L-T_4 treatment group.The concentration of ventricular MyoCa^（2＋）in hypothyroid group was significantly higher than that in control group（P〈0.01）,and that in L-T_4 treatment group showed a significant decrease as compared with hypothyroid group（P〈0.05）.The activity of sarcoplasmic reticulum Ca^（2＋）-ATPase in hypothyroid gr

关 键 词：甲状腺功能减退症 肌浆网CA^2+-ATP酶 磷酸受纳蛋白 大鼠 新生 

分 类 号：R363.2[医药卫生—病理学]