黄芪多糖改善db/db糖尿病肥胖小鼠心肌脂毒性的机理研究

Mechanism of astragalus polysaccharide therapy in improving myocardial lipid toxicity in db/db diabetic obese mice

目的:探讨黄芪多糖对糖尿病心肌脂肪酸代谢紊乱及脂毒性的影响。方法:将5周龄的雄性2型糖尿病模型db/db小鼠按照随机数字表法分为黄芪多糖组、二甲双胍组、糖尿病组,每组8只,每日分别经胃管鼻饲黄芪多糖2 000 mg/kg、二甲双胍2 000mg/kg、等量生理盐水,共12周。8只同龄C57BL/6J小鼠设为正常组,每日经胃管鼻饲等量生理盐水。采用超声心动图检测各组小鼠的心脏功能情况,Bligh-Dyer法和电喷雾电离质谱(ESIMS)方法检测心肌组织三酰甘油沉积情况,微型正电子发射断层显像技术检测心肌脂肪酸的摄取利用和氧化代谢指标,western blot法检测脂肪酸代谢关键酶的蛋白表达水平。结果:(1)与正常组相比,糖尿病组小鼠左室舒张末期内径(LVEDD)和左室收缩末期内径(LVESD)显著升高,左室短轴缩短率(FS)显著降低(P均<0.05);黄芪多糖组上述指标较糖尿病组有显著改善(P均<0.05);二甲双胍组上述指标与糖尿病组相比差异无统计学意义。(2)与正常组相比,糖尿病组小鼠心肌组织的脂肪酸摄取利用率、游离脂肪酸氧化率、三酰甘油含量和三酰甘油各亚型含量显著升高(P均<0.05);黄芪多糖组上述指标较糖尿病组显著降低(P均<0.05);二甲双胍组上述指标与糖尿病组相比差异无统计学意义。(3)与正常组相比,糖尿病组小鼠心肌组织中氧化物酶体增殖物激活受体α(PPARα)、心肌组织内肌肉型-肉毒碱棕榈酰转移酶-1(M-CPT-1)和乙酰辅酶A氧化酶的蛋白表达水平均显著升高(P均<0.05);黄芪多糖组上述蛋白的表达水平与糖尿病组相比均显著降低(P均<0.05);二甲双胍组上述蛋白的表达水平与糖尿病组相比差异无统计学意义。结论:黄芪多糖可显著改善糖尿病组小鼠的心脏功能,降低糖尿病小鼠心肌组织的脂肪酸摄取利用率、游离脂肪酸氧化率和三酰甘油含量,控制糖尿病小鼠心肌脂肪酸代谢相关蛋白处于正常水平,从而改善糖尿病心肌脂肪酸代谢紊乱及脂毒性。

Objective:To explore the effect of astragalus polysaccharide(APS)on fatty acid metabolism and lipid toxicity in diabetic cardiomyopathy.Methods:The 5 weeks old male type 2 random number table method.Each group had 8 rats,which were given APS 2000 mg/kg,metformin 2000 mg/kg and an equal amount of saline through nasogastric tube for 12 weeks respectively.Eight same-age C57BL/6J mice were set as normal group and fed with the same amount of normal saline.Cardiac function was examined by echocardiography in each group.Bligh-Dyer and ESIMS were used to detect myocardial triglyceride deposition.Micro-positron emission tomography was used to detect myocardial fatty acid uptake and index of oxidative metabolism.Western blot was used to detect the protein expression level of key enzymes involved in the metabolism of fatty acids.Results:(1)The LVEDD and LVESD were increased significantly,while the LV fractional shortening(FS)were decreased significantly in diabetic group compared with those in normal group(all P<C0.05).The above indexes of APS group were significantly improved compared with those of diabetic group(all P〈0.05).There was no significant difference in above indexes between metformin group and diabetic group.(2)Compared with the normal group,the fatty acid uptake rate,the free fatty acid oxidation rate,the triglyceride content and the triglyceride subtypes in diabetic group were significantly increased(all P<0.05).The above indexes in APS group were significantly lower than those in diabetic group(all P<0.05).There was no significant difference in above indexes between the metformin group and diabetic group.(3)Compared with normal group,the protein expression levels of PPARαM-CPT-1 and ACO in myocardium were significantly increased in diabetic group(all P<C0.05).The expression of these proteins was significantly lower in APS group than those in diabetic group(all P〈0.05).There was no significant difference in protein expression between the metformin group and diabetic group.Conclusions:APS can improve fatty acid metabolism in diabetic myocardium,including improving cardiac function,decreasing fatty acid uptake and utilization rate,free fatty acid oxidation rate and triglyceride content in the myocardium of diabetic mice,and controlling the fatty acid metabolism related proteins in the myocardium of diabetic mice at normal levels.