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目的探讨长期酒精暴露与胰岛素敏感性之间的关系并探讨其相关的分子机制;观察神经酰胺在酒精引起胰岛素抵抗过程中的可能作用。方法建立C57BL/6J野生型(WT)小鼠和神经鞘磷脂合成酶2基因敲除(SMS-/-2)3月龄小鼠的长期酒精暴露模型,两基因型小鼠又分为对照组、中剂量酒精组和高剂量酒精组,共计90只。建模5个月后,用血糖仪测定小鼠空腹血糖值,用酶学法检测血清胰岛素浓度,并计算胰岛素抵抗指数。利用免疫荧光染色法观察各组小鼠海马CA1区胰岛素受体底物2(IRS2)阳性细胞表达情况,免疫印迹法检测小鼠海马组织IRS2蛋白的相对表达量。结果 1.长期酒精暴露导致WT和SMS-/-2小鼠空腹血糖值和胰岛素抵抗指数升高,且具有剂量依赖性(P<0.05);但SMS-/-2小鼠随着酒精剂量的增加胰岛素抵抗指数升高幅度较小。2.免疫组织化学染色显示,酒精暴露诱导WT和SMS-/-2小鼠海马IRS2阳性细胞数降低,有剂量依赖性(P<0.05);与相同处理条件的WT小鼠相比,酒精诱导SMS-/-2小鼠海马IRS2阳性细胞数降低增多(P<0.05)。3.免疫印迹法检测各组间小鼠海马组织IRS2蛋白相对表达量与上述结果一致。结论长期酒精暴露可引起胰岛素抵抗,IRS2蛋白表达降低,且存在剂量依赖性,因此酒精导致IRS2表达下降可能是胰岛素抵抗的分子机制之一;神经酰胺可能参与酒精暴露诱导IRS2表达下降的过程,且有促进胰岛素抵抗形成的作用。
Objective To investigate the relationship between long-term alcohol exposure and insulin sensitivity and to explore its molecular mechanisms and to investigate the possible role of ceramide in alcohol-induced insulin resistance. Methods The long-term alcohol exposure model of C57BL / 6J WT mice and sphingomyelin synthase 2 gene knockout mice (SMS - / - 2) were established. The two genotypes mice were divided into control group , Middle-dose alcohol group and high-dose alcohol group, a total of 90. After modeling for 5 months, the fasting blood glucose of mice was measured by blood glucose meter, the serum insulin concentration was measured by enzymology method, and the index of insulin resistance was calculated. Immunofluorescence staining was used to observe the expression of insulin receptor substrate 2 (IRS2) in hippocampal CA1 region in each group. The relative expression of IRS2 protein in hippocampus of mice was detected by immunoblotting. Long-term alcohol exposure resulted in a dose-dependent increase in fasting blood glucose and insulin resistance index in WT and SMS - / - 2 mice (P <0.05) Increased insulin resistance index increased less. Immunohistochemical staining showed that alcohol exposure induced a dose-dependent decrease of IRS2 positive cells in hippocampus of WT and SMS - / - 2 mice (P <0.05). Compared with WT mice treated with ethanol, alcohol induction The number of IRS2 positive cells in SMS - / - 2 mice decreased significantly (P <0.05). Immunoblotting detected the relative expression of IRS2 protein in hippocampus of mice in each group was consistent with the above results. Conclusion Long-term alcohol exposure may cause insulin resistance and decrease IRS2 protein expression in a dose-dependent manner. Therefore, the decrease of IRS2 expression induced by alcohol may be one of the molecular mechanisms of insulin resistance. Ceramide may be involved in the process of alcohol exposure-induced decrease of IRS2 expression Have a role in promoting the formation of insulin resistance.