胰岛素抵抗大鼠模型中同型半胱氨酸代谢关键酶的变化

Changes of homocysteine metabolism key enzyme in insulin resistance rat model

目的建立胰岛素抵抗(IR)的动物模型,探讨同型半胱氨酸的变化及同型半胱氨酸改变的分子机制。方法 20只6周健康SD大鼠随机分为正常对照组和胰岛素抵抗组。高脂高糖饮食加高脂灌胃3个月制造胰岛素抵抗模型,空腹状态下测定血液中同型半胱氨酸(Hcy)、葡萄糖(GLU)、胰岛素(INS)、甘油三酯(TG)和总胆固醇(TC)的浓度,计算胰岛素抵抗指数(INI);免疫组织化学、RT-PCR和Western blotting检测肝脏组织亚甲基四氢叶酸还原酶(MTHFR)、胱硫醚合成酶(CBS)、蛋氨酸合成酶(MTR)表达的变化。结果胰岛素抵抗组和正常对照组比较,空腹GLU、INS的浓度升高(P<0.05),INI增加(P<0.05),确定胰岛素抵抗模型建立成功;TG和Hcy浓度增加(P<0.05),TC变化无统计学意义(P>0.05);MTHER和CBS的免疫组织化学检查、mRNA及蛋白表达降低(P<0.05),MTR的免疫组织化学检查、mRNA及蛋白表达无统计学意义(P>0.05)。结论在胰岛素抵抗条件下,同型半胱氨酸浓度增加,可能与参加同型半胱氨转化的MTHER和CBS表达降低有关。

Objective To research the homocysteine change in an insulin resistance model for SD rats, and to discusse the molecular mechanism of the homocysteine change. Methods Twenty healthy rats, six weeks of age, were randomly divided into the control group （ n = 10） and the insulin resistance group （ n = 10）. Normal food was fed in control group;The insulin resistance model was established by high fat diet and gavaged by the high fat for 3 months. The concentrations of homocysteine, glucose, insulin, total cholesterol and triglyceride were measured in the fasting state. At the same time, the insulin resistance index （ISI） was calculated. The expressions of methylenetetrahydrofolate reductase （MTHFR） , eystathionine 13 synthase （CBS） and methionine synthetase （MTR） were detected by immunohistochemistry, RT-PCR and Western blotting in the rat liver tissue. Results The concentrations of the blood glucose and blood insulin in the insulin resistance group were higher than that in the control group （ P 〈 0. 05 ） , the insulin resistance index was increased, so the insulin resistance model was successed. The concentrations of triglyceride and homocysteine were increased （ P 〈 0.05 ）. However, the concentration of the total cholesterol was no statistical significance （ P 〉 0. 05 ）. The protein and mRNA expressions of MTHER and CBS in insulin resistance group were lower compared with the control group by RT-PCR, Western blotting and immunohistochemical staining（P 〈 0.05）. However, the expression of MTR protein and mRNA were not different between the insulin resistance group and the control group （ P 〉 0.05 ）. Conclusion The homocysteine concentration is higher in the condition of insulin resistance, which may be related to decrease with the expression of MTHER and CBS in metabolic transformation of homocysteine.