饲料钙不足通过抑制骨骼肌PGC-1α表达影响大鼠血糖血脂的研究

Calcium deficiency affects serum glucose and lipids by inhibiting PGC-1α expression in skeletal muscle of rats

目的研究饲料钙不足对大鼠血糖血脂的影响并对其可能的机制进行探讨。方法 SD雄性大鼠20只(7周龄),适应性喂养1周后按体重随机分为2组,即对照组(n=10,饲料含钙量0.5%)、钙不足组(n=10,饲料含钙量0.15%)。每日记录摄食量,每周称量体重,第16周末处死大鼠,采集血清测定血糖(glucose,GLU)、总胆固醇(total cholestrol,TC)、甘油三酯(triglyceride,TG)、低密度脂蛋白胆固醇(low density lipoprotein cholesterol,LDL-C)和高密度脂蛋白胆固醇(high density lipoprotein cholesterol,HDL-C);采集骨骼肌检测PGC-1αmRNA和蛋白的表达水平并分析其与血糖血脂的相关性。结果与对照组相比,钙不足组大鼠摄食量及体重均无差别(均有P>0.05),但血清GLU、TC、LDL-C水平升高,HDL-C/LDL-C比值降低(均有P<0.05),TG和HDL-C虽没有统计学差异但是有升高趋势;钙不足组大鼠骨骼肌内调控糖脂代谢及线粒体功能的关键因子过氧化物酶体增殖物激活受体γ辅激活因子-1α(proliferator-activated receptorγcoactivator-1α,PGC-1α)mRNA和蛋白的表达水平均降低(均有P<0.05)。大鼠骨骼肌PGC-1α表达水平与TC、LDL-C等水平呈负相关(均有P<0.05)。结论饲料钙不足虽未影响大鼠体重,但可通过抑制PGC-1α的表达从而引起大鼠血糖血脂紊乱。

Objective The present study was aimed to investigate the effects of calcium deficiency on blood glu- cose and lipids of rats. Methods Following one week of adaptation, 20 male SD rats （ 7 weeks old） were randomly as- signed into two groups： 10 were control group （0. 5% calcium in feed） and 10 were calcium deficiency group （0. 15% cal- cium in feed）. Food intake was measured daily, and body weight was measured weekly. After 16 weeks, the rats were an- esthetized with pentobarbital via intraperitoneal injection. The blood samples were obtained to examine serum glucose （GLU） , total cholesterol （TC） , triglyceride （TG）, low density lipoprotein cholesterol （LDL-C） and high density lipopro- tein cholesterol （HDL-C）. The mRNA and protein levels of PGC-1α were detected in skeletal muscles. The association be- tween the expression of PGC-1α and blood glucose and lipids levels were analyzed by Pearson＇ s correlation. Results Compared with the control group, food intake and body weight of rats were not significantly different in calcium deficiency group （ all P 〉 0.05） , while the levels of serum GLU, TC, LDL-C were increased; although the levels of TG and HDL-C were not significantly different between the two groups of animals, a rising tendency was detected; the ratio of HDL-C to LDL-C was decreased （ all P 〈 0. 05 ）. The mRNA and protein expression of proliferator-activated receptorγ coactivator-1α （ PGC-1 α） , one of the key factors for regulation of glucose and lipid metabolism and mitochondrial function in skeletal mus- cle, were decreased in rats from calcium deficiency group （ all P 〈 0. 05）. There was an obvious negative correlation be- tween PGC-1α expressions and serum TC and LDL-C （ all P 〈 0. 05）. Conclusions Calcium deficiency did not affect the body weight of rats, but it could induce serum glucose and lipids disorder through inhibiting the expression of PGC-1α in skeletal muscle.