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目的:观察血糖波动对2型糖尿病大鼠心肌组织形态的影响并探讨其可能机制。方法:选取45只雄性Sprague-Dawley(SD)大鼠,按随机数字法分成正常对照组(CON组)和糖尿病组(DM组)。DM组给予4周高糖高脂饲料喂养后,予小剂量链脲佐菌素35 mg/Kg腹腔注射建立2型糖尿病大鼠模型。将成模大鼠按随机数字法分成糖尿病对照组(CDM组)和波动血糖组(FDM组)。FDM组大鼠每天定时皮下注射短效胰岛素并错时给予葡萄糖,建立糖尿病血糖波动模型,CON组、CDM组予等量生理盐水皮下注射。每周测血糖值2天,4次/天,动态观测各组大鼠外形、进食量、饮水量等变化。造模成功12周后取腹主动脉血测定糖化血红蛋白(Hb Alc),取大鼠心脏组织行Masson染色观察心肌纤维化水平,免疫印记法分别检测心肌组织AKT、p-AKT蛋白的表达,免疫组织化学法分析各组大鼠心肌细胞中Caspase-3蛋白的表达。结果:(1)与CON组相比,FDM组、CDM组大鼠Hb A1c、血糖变异系数(CV)水平升高,差异具有统计学意义(P<0.05);与CDM组相比,FDM组Hb A1c水平差异无统计学意义(P>0.05),CV值进一步升高,差异具有统计学意义(P<0.05)。(2)与CON组相比,CDM组、FDM组大鼠心肌组织形心肌纤维化水平升高,差异具有统计学意义(P<0.05);与CDM组相比,FDM组心肌组织心肌纤维化水平进一步升高,差异具有统计学意义(P<0.05)。(3)与CON组相比,FDM组、CDM组大鼠心肌p-AKT蛋白表达水平均减少,差异具有统计学意义(P<0.05);与CDM组相比,FDM组p-AKT蛋白表达水平均进一步减少,差异具有统计学意义(P<0.05)。而三组大鼠心肌组织AKT蛋白表达水平差异无统计学意义(P>0.05)。(4)与CON组相比,FDM组、CDM组大鼠心肌Caspase-3蛋白表达水平均升高,差异具有统计学意义(P<0.05);与CDM组相比,FDM组Caspase-3蛋白表达水平进一步升高,差异具有统计学意义(P<0.05)。结论:血糖波动可加重2型糖尿病大鼠的心肌纤维化,其机制可能与抑制AKT活化有关。
Objective: To observe the effect of blood glucose fluctuation on myocardial tissue morphology in type 2 diabetic rats and to explore its possible mechanism. Methods: Forty five male Sprague-Dawley rats were randomly divided into normal control group (CON group) and diabetic group (DM group). DM group were given 4 weeks of high-sugar and high-fat diet feeding, low-dose streptozotocin 35 mg / Kg intraperitoneal injection of type 2 diabetic rat model. The model rats were randomly divided into diabetic control group (CDM group) and fluctuating blood glucose group (FDM group). The rats in FDM group were injected with short-acting insulin subcutaneously every day and glucose was added in the wrong time. Diabetic model of blood glucose fluctuation was established. CON and CDM groups were injected subcutaneously with normal saline. Blood glucose was measured every two days, 4 times a day, dynamic observation of the shape of rats, food intake, water intake and other changes. Hb Alc was measured in abdominal aorta after 12 weeks of successful model establishment. Masson staining was used to observe myocardial fibrosis in rat heart. Immunohistochemical method was used to detect the expression of AKT and p-AKT in myocardium. Histochemical analysis of Caspase-3 protein expression in rat cardiac myocytes. Results: (1) Compared with CON group, the level of Hb A1c and CV of CVB in FDM group and CDM group were significantly increased (P <0.05). Compared with CDM group, FDM group There was no significant difference in Hb A1c levels (P> 0.05). The CV value was further increased with a statistically significant difference (P <0.05). (2) Compared with CON group, the level of myocardial myocardial fibrosis in CDM group and FDM group was significantly increased (P <0.05). Compared with CDM group, myocardial fibrosis The level was further increased, the difference was statistically significant (P <0.05). (3) Compared with CON group, the expression of p-AKT protein in FDM group and CDM group decreased significantly (P <0.05). Compared with CDM group, p-AKT protein expression in FDM group The levels were further reduced, the difference was statistically significant (P <0.05). There was no significant difference in AKT protein expression between the three groups (P> 0.05). (4) Compared with CON group, the expression of Caspase-3 protein in myocardium of FDM group and CDM group were significantly increased (P <0.05). Compared with CDM group, Caspase-3 protein The expression level increased further, the difference was statistically significant (P <0.05). Conclusion: The fluctuation of blood glucose may aggravate myocardial fibrosis in type 2 diabetic rats, which may be related to the inhibition of AKT activation.