长期摄入不同剂量乙醇对大鼠骨骼肌G11α表达及胰岛素抵抗的影响

Effects of different dosage of ethanol intake for a long term on G11 alpha expression and insulin resistance in skeletal muscle of rats

目的:观察G蛋白家族中G11α和Gqα mRNA在乙醇诱导下对大鼠骨骼肌胰岛素抵抗的作用.方法:①实验于2003-09/2005-03在山东省立医院中心实验室完成.选用雄性Wistar健康成年大鼠40只.随机将大鼠分为4组,对照组、大剂量饮酒组、中剂量饮酒组、小剂量饮酒组,每组10只.对照组:胃管灌注蒸馏水5.0 g/(kg·d),1次/d;大、中、小剂量饮酒组:胃管灌注乙醇量5.0,2.5,0.5g/(kg·d),1次/d,每组均喂养5个月.②采用强生血糖仪测定空腹血糖和糖负荷后2 h血糖.③采用液体闪烁计数仪分别测量基础状态下、胰岛素刺激后的组织非特异吸收的2-D-3H葡萄糖量.基础状态葡萄糖摄取=单位重量基础状态肌肉计数-单位重量煮沸变性肌肉计数;胰岛素刺激后葡萄糖摄取=单位重量胰岛素刺激后肌肉计数-单位重量基础状态肌肉计数.④采用反转录聚合酶链反应法测定G11α和GqαmRNA水平.采用蛋白质印迹实验测定G11α和Gqα蛋白水平.⑤各组间比较采用单因素方差分析.结果:大鼠40只均进入结果分析.①各饮酒组大鼠空腹血糖和糖负荷后2 h血糖与对照组相近.②大、中剂量饮酒组大鼠基础状态骨骼肌糖摄取量与对照组比较,分别下降29%,72%(P＜0.05);胰岛素刺激后,分别下降27%,61%(P＜0.05);小剂量饮酒组大鼠无明显变化.③大、中、小剂量饮酒组大鼠骨骼肌G11α mRNA表达与对照组比较,分别下降57%,42%,38%(P＜0.05～0.01);Gqα mRNA表达无明显变化.④大鼠长期摄入乙醇后骨骼肌G11α和Gqα蛋白水平变化与mRNA水平变化趋势一致.结论:①乙醇喂养5个月后,大鼠机体水平上没有表现出明显的糖代谢紊乱.②摄入乙醇剂量为5.0 g/(kg·d)和2.5 g/(kg·d)5个月后,大鼠骨骼肌产生明显的胰岛素抵抗.③长期摄入乙醇可影响大鼠骨骼肌G11α表达,并呈剂量依赖性.④各饮酒组大鼠骨骼肌Gq α mRNA表达及其蛋白水平变化不明显.

AIM： To observe the resistive effects of G11α and Gqα mRNA of G protein family on insulin in skeletal muscle in rats under the induction of ethanol. METHODS： ① The experiment was conducted at the Central Laboratory, Shandong Provincial Hospital from September 2003 to March 2005. Forty adult Wistar healthy male rats were selected, and were divided randomly into 4 groups： control group, large dose group, middle dose group and small dose group with 10 rats in each group, Control group： the rats were filled with 5,0 g/kg distilled water per day with gastric canal, once a day; Large, middle and small dose group： The rats were filled with 5.0,2,5,0.5 g/kg per day ethanol with canal of stomach, once a day, for 5 months in every group. ② The levels of fasting plasma glucose and plasma glucose of glucose load 2 hours were measured with LIFESCAN glucose meter. ③ The dosage of insulin-stimulated glucose 2-D-^3H were measured under basic status with Liquid Scintillation Counters; Glucose intake under basic status = muscle counting of unit weight under basic status-boiling degeneration：muscle counting of unit weight; Glucose intake after insulin stimulation = muscle counting of unit weight after insulin stimulation - muscle counting of unit weight under basic status. ④ The levels of G11α and Gqα mRNA were detected with reverse transcription polymerase chain reaction. The levels of G11α and Gqα protein were tested with Western blot. ⑤ The comparison among groups was done with single factor analysis of variance. RESUILTS： Forty rats were all involved in the result analysis. ① The levels of fasting plasma glucose and plasma glucose of glucose load 2 hours in every drinking group were similar to those in control group. ② The dosage of glucose intake in skeletal muscle under basic status in rats of large and middle dosage drinking group decreased 29% ,72%（P 〈 0.05）, respectively, as compared with that in the control group; After insulin stimulation, decreased 27%,61% （P〈 0.05）, respectively; There were insignificant changes in rats of small dose drinking group. ③ The Gila mRNA expression in skeletal muscle in large, middle and small dose drinking group decreased 57% ,42%,38%（ P 〈 0.05-0.01）, respectively, as compared with that in the control group. There were insignificant changes in Gqα mRNA expression. ④ The changes of G11α and Gqα protein were the same to mRNA changes in skeletal muscle after ethanol intake for a long time. CONCLUSION： ① After feeding with ethanol for 5 months, there is insignificant glycometabolism derangement appeared in rat body level. ② Insulin resistance occurs in skeletal muscle in rats apparently after intaking ethanol at the dosage of 5.0 g/kg per day and 2.5 g/kg per day for 5 months. ③ Long term of ethanol intake may have effects on G11α expression in skeletal muscle in rats, and shows dose-dependent effect. ④ The changes of Gqα mRNA expression and its protein level in skeletal muscle in rats of every drinking group are insignificant.