熊果酸对糖尿病小鼠心肌病变的作用及其机制

Effect of ursolic acid on cardiomyopathy of mice with diabetes and its mechanism

目的:研究熊果酸对高脂饮食结合小剂量链脲佐菌素(STZ)诱导的糖尿病小鼠心肌病的影响,探讨其可能的作用机制。方法:雄性ICR小鼠30只,随机分为对照组(n=10)和造模组(n=20),对照组和造模组分别以普通饲料及高脂饲料饲养,连续6周。造模组腹腔注射STZ连续5 d,对照组腹腔注射相应溶剂,9 d后测空腹血糖(FBG),高于11.1 mmol/L视为糖尿病模型。20只成功造模小鼠随机分为模型组和熊果酸组(n=10)。各组连续灌胃给药(熊果酸100 mg/kg或相应溶剂) 8周。测定FBG、体重、全心重和左心室重,计算心脏质量指数(HMI)和左室质量指数(LVMI);测定血清肌酸激酶(CK)、乳酸脱氢酶(LDH)水平;测定心肌组织超氧化物歧化酶(SOD)活力和丙二醛(MDA)含量; HE染色观察心肌病理改变;免疫组化法测定NOD样受体蛋白3(NLRP3)、白介素-1β(IL-1β)的蛋白质表达。结果:与正常组比较,模型组HMI、LVMI、FBG、CK、LDH、MDA水平显著升高; SOD活力显著降低。HE染色显示,模型组小鼠心肌纤维排列紊乱,细胞水肿、肥大,细胞间质大量炎性细胞浸润;免疫组化显示,模型组小鼠心肌组织NLRP3和IL-1β蛋白质表达显著增加;熊果酸组小鼠的上述变化明显改善。结论:熊果酸对高脂饲料结合小剂量链脲佐菌素诱导的糖尿病小鼠心肌损伤有明显的改善作用,其机制与抑制NLRP3炎症小体活化,减少IL-1β生成,减轻心肌组织炎性损伤有关。

Objective： To study the effect of ursolic acid on cardiomyopathy in mice with diabetes induced by high-fat diet combined with low dose streptozotocin,and to explore its possible mechanism. Methods： Thirty male ICR mice were randomly divided into control group（ n = 10） and moulding group（ n = 20）,the mice in the two groups were fed with regular diet and high-fat diet respectively for 6 weeks,and then the mice in the moulding group were injected with streptozotocin（ 30 mg/kg） for 5 successive days to induce diabetes mellitus（ DM）. Fasting blood glucose（ FBG） was measured after 9 days. Mice with FBG over 11.1 mmol/L were regarded as DM.Twenty DM mice were randomly divided into model group and ursolic acid group（ n = 10）. Mice in each group were continuously administrated ursolic acid（ 100 mg/kg） or corresponding solvent intragastrically for 8 weeks. After that,FBG was measured,body weight（ BW）,heart weight and left ventricular weight were weighed in order to calculate the heart mass index（ HMI） and left ventricular mass index（ LVMI）. Levels of creatine kinase（ CK）,lactate dehydrogenase（ LDH） in serum and the level of superoxide dismutase（ SOD）,malondialdehyde（ MDA） in myocardial tissue were detected. HE staining was used to observe pathological changes of myocardial tissue. Immunohistochemistry was employed to determine the expression of NOD-like receptor protein 3（ NLRP3） and interleukin1β（ IL-1β）. Results： Compared with the control group,HMI,LVMI were apparently enlarged,levels of FBG,CK,LDH in serum and MDA in myocardial tissue were extremely increased,while the activity of SOD in myocardial tissue were extraordinary decreased in diabetic group. HE staining of myocardium showed that arrangement disorder of myocardial fibers,edema and hypertrophy in myocardial cell,as well as inflammatory cell infiltration in model group. Immunohistochemistry showed that the expression of NLRP3 and IL-1β in myocardial tissue increased obviously in model group,the above changes inursolic acid group were significantly ameliorated. Conclusion： Ursolic acid has a obvious protective effect on myocardial injury in mice with diabetes induced by high-fat diet combined with low dose streptozotocin,and its mechanism may be associated with inhibiting NLRP3 inflammasome activation,reducing IL-1β generation and alleviating myocardial inflammatory injury.