二甲双胍对异氟醚麻醉小鼠血糖的影响

目的 观察二甲双胍对异氟醚麻醉小鼠血糖的影响.方法 156只8周龄雄性C57BL/6小鼠分两部分进行实验.①血糖检测:这部分实验分两步进行.首先,28只小鼠按照按随机数字表法分为未禁食组(n组)和禁食12 h组(f组);各组再分为2个亚组,对照组(Cn组/Cf组),麻醉组(An组/Af组).进一步实验使用56只小鼠按随机数字表法分为n组和f组,每组28只.两组均再按随机数字表法分为4个亚组,Cn组/Cf组,An组/Af组,二甲双胍组(Mn组/Mf组)和二甲双胍麻醉组(MAn组/MAf组),每亚组均为7只.Mn组、Mf组、MAn组和MAf组于麻醉前1.5 h腹腔注射二甲双胍40 mg/kg,An组、Af组、MAn组和MAf组均行异氟醚6h麻醉.通过尾静脉取血检测围麻醉期各时间点血糖值.②荧光定量核酸扩增检测系统(quantitative polymerase chain reaction detecting system,Q-PCR)检测:共72只小鼠.各亚组分组方法同上,分别于麻醉1、4、6h取材下丘脑,每组每个时间点取3只.Q-PCR检测腺苷酸活化蛋白激酶(adenosine monophosphate activated protein kinase,AMPK)两个亚型AMPKα1、AMPKα2的mRNA表达水平.结果 血糖水平变化:与n组比较,f组小鼠血糖显著降低(8.25±1.02) mmol/L比(6.46±0.65) mmol/L,P＜0.05].在f组和n组中,麻醉组小鼠均出现血糖水平升高;与Cn组和Cf组比较,An组和Af组分别在麻醉0.5、1、2h和1、2、3h升高(P＜0.05);分别与Cn组和Cf组比较,Mn组和Mf组血糖水平差异无统计学意义(P＞0.05);MAn组和MAf组均于麻醉2h开始出现低血糖并持续(P＜0.05),这种差异分别在麻醉结束4h和1h后消失.下丘脑AMPK mRNA表达:1h,与Cf组比较,MAf组AMPKα1和AMPKα2mRNA表达下调(P＜0.05);4h,与Cn组和Cf组比较,An组、MAn组和Af组AMPKα1表达下调(P＜0.05),AMPKα2 mRNA表达在MAf组降低(P＜0.05);6h,与Cn组和Cf组比较,AMPKα1和AMPKα2在An组和MAn组、Af组和MAf组mRNA表达都降低(P＜0.05).结论 长时程异氟醚麻醉可使小鼠血糖呈“先高后低”改变,二甲双胍预处理后麻醉小鼠可出现持续低血糖,这一过程与下丘脑AMPK转录活性无明显关联.

Effects of metformin pretreatment on blood glucose level in mice under isoflurane anesthesia

Objective To examine the effects of metformin on blood glucose levels in mice under isoflurane anesthesia.Methods One hundred and fifty-six 8-week-old male C57BL/6 mice were used for blood glucose tests and AMPK mRNA measurement.(①) Blood glucose test,there were two steps in this part:firstly,twenty-eight mice were randomly divided into two groups,subject to normal diet (n) or 12 h fasting (f) (n=14);each group was further divided into two subgroups:no additional treatment (group Cn/group Cf),anesthesia group (group An/group Af).Secondly,fifty-six mice were randomly divided into two groups,subject to group n or group f (n=28);each group was further divided into 4 subgroups:group Cn/group Cf,group An/group Af,metformin group (group Mn/group Mf),metformin combined with anesthesia group (group MAn/group MAf) (n =7).Metformin (40 mg/kg) was administered intraperitoneally 1.5 h before anesthesia (1.5％isoflurane,for 6 h).The blood was collected from tail vein immediately before anesthesia and 0.5,1,2,3,4,6 h after induction of anesthesia,and was used for glucose determination.② mRNA measurement,seventy-two mice were used for mRNA measurement.The mRNA levels of AMPKα and AMPKo2 in the hypothalamus were measured with quantitative polymerase chain reaction detecting system (Q-PCR) 1,4 h and 6 h after the onset of anesthesia (3mice at each time point for each subgroup).Results Fasting reduced blood glucose levels,while metformin did not alter blood glucose levels in both n and f mice.Anesthesia increased blood glucose levels within the first 2-3 h.However,metformin maintained hypoglycemia in anesthetized mice.The levels of AMPK mRNA in the hypothalamus were altered by metformin and isoflurane depending on the duration of anesthesia.Metformin+1 h anesthesia significantly attenuated mRNA levels of AMPKα1 and AMPKα2(P＜0.05).Four hours anesthesia alone and combined with metformin decreased AMPKα1 mRNA levels (P＜0.05),but the decrease in AMPKα2 mRNA levels was only observed in group MAn (P＜0.05).Six hours anesthesia decreased AMPKα1 and AMPKα2 mRNA levels in groups An,MAn,Af,and MAf (P＜0.05).Conclusions Under long-term isoflurane anesthesia the blood glucose of mice increased at first and then decreased,while metformin combined with anesthesia induced persistent hypoglycemia.The effects of anesthesia and metformin on the mRNA of AMPK in the hypothalamus differ from their effects on blood glucose.