【作者】 徐茂锦；

【导师】 邹大进；

【作者基本信息】 第二军医大学 ， 内分泌与代谢病， 2008， 博士

【摘要】 [目的]研究清道夫受体CD36在高脂饮食糖尿病大鼠和2型糖尿病患者中的表达及其可能的机制,观察噻唑烷二酮类药物—罗格列酮的干预作用。[方法]SD大鼠高脂饲料喂养4周后,一次性腹腔注射链脲佐菌素35mg/kg体重制备2型糖尿病大鼠模型。采用流式细胞术测定高脂饮食糖尿病大鼠和2型糖尿病患者外周血单核细胞CD36表达的平均荧光强度(MFI),实时定量逆转录酶聚合酶链反应(RT-PCR)法测定高脂饮食糖尿病大鼠骨骼肌、皮下脂肪、附睾脂肪组织中CD36mRNA、过氧化物酶体增殖物激活受体γ(PPARγ)mRNA和葡萄糖转运蛋白4(GLUT4)mRNA的表达,Westen blot法测定高脂饮食糖尿病大鼠骨骼肌、皮下脂肪、附睾脂肪组织中CD36蛋白质、PPARγ蛋白质和GLUT4蛋白质的表达;并观察罗格列酮干预治疗后上述表达的变化。分析CD36的表达与PPARγ、GLUT4的表达及其它细胞因子、代谢指标间的关系。[结果](1)高脂饮食一次性腹腔注射链脲佐菌素SD大鼠出现明显的高血糖、高胰岛素血症、脂代谢紊乱和体重增加,与人类2型糖尿病代谢紊乱极为相似。(2)与正常饮食对照组比较,高脂饮食糖尿病大鼠外周血单核细胞CD36表达的MFI明显升高(P＜0.01);罗格列酮干预后糖尿病大鼠外周血单核细胞CD36表达的MFI与糖尿病组、干预前相比均显著降低(P＜0.01);高脂饮食糖尿病大鼠外周血单核细胞CD36表达的MFI与空腹血糖(FBG)、稳态模型评估胰岛素抵抗指数(HOMA-IR)呈正相关。(3)与正常饮食对照组比较,高脂饮食糖尿病大鼠骨骼肌、皮下脂肪、附睾脂肪组织中CD36mRNA、PPARγmRNA和蛋白质的表达均显著升高(P＜0.01),上述组织中GLUT4 mRNA和蛋白质的表达显著降低(P＜0.01);CD36mRNA及其蛋白质的表达与PPARγmRNA及其蛋白质的表达变化相一致;与高脂饮食糖尿病大鼠比较,罗格列酮干预组糖尿病大鼠骨骼肌组织中CD36、PPARγmRNA及其蛋白质的表达均明显下降(P＜0.05)、GLUT4mRNA及其蛋白质的表达明显上升(P＜0.01),皮下脂肪和附睾脂肪组织CD36、PPARγ和GLUT4 mRNA及其蛋白质的表达均升高,但仅在附睾脂肪组织的变化有统计学意义(P＜0.05)。(4)2型糖尿病患者外周血单核细胞CD36表达的MFI较正常对照者明显增高(P＜0.01),伴有动脉粥样硬化的患者明显高于无动脉粥样硬化患者(P＜0.01),单核细胞CD36表达的MFI与糖尿病病程、FBG、HbAlc、HOMA-IR呈正相关。(5)与对照组以及治疗前比较,2型糖尿病患者罗格列酮治疗后单核细胞CD36表达的MFI显著下降(P＜0.01),血清可溶性血管细胞粘附分子-1(sVCAM-1)、肿瘤坏死因子α(TNFα)水平明显降低(P＜0.01),血清脂联素水平明显升高(P＜0.01);单核细胞CD36表达的MFI与血清sVCAM-1、TNFα水平呈正相关、与血清脂联素水平呈负相关。[结论]高脂饮食、一次性腹腔注射链脲佐菌素SD大鼠是比较理想的2型糖尿病动物模型;2型糖尿病状态下外周血单核细胞CD36表达增加,可能是促进糖尿病动脉粥样硬化的机制之一,高血糖、胰岛素抵抗是单核细胞CD36表达的主要上调因子;罗格列酮能降低2型糖尿病外周血单核细胞CD36表达,其机制可能在于降低血糖、减轻氧化应激、改善胰岛素抵抗和减轻炎症反应;CD36在糖尿病大鼠骨骼肌、脂肪组织的表达受PPARγ的调节并具有组织特异性;皮下脂肪和附睾脂肪组织在胰岛素抵抗、脂质代谢、动脉粥样硬化中可能起不同的作用。更多还原

【Abstract】 Objective:To investigate the expression of scavenger receptor CD36 in High-Fat-Diet induced diabetic rats and Type 2 diabetes and the possible mechanism, and to observe the effects of thiazolidinediones—rosiglitazone intervention.Method:Type 2 diabetic rat models were induced by High-Fat-Diet SD rats combined with intraperitoneal injection streptozotocin(STZ) 35mg/kg once.The expression of CD36 in monocytes from High-Fat-Diet induced diabetic rats and Type 2 diabetes were measured before and after rosiglitazone intervention by laser flow cytometry.Expressions of CD36 mRNA,Peroxisome proliferator-activated receptorγ(PPARγ) mRNA,Glucose transporter 4(GLUT4) mRNA and their protein in skeletal muscle,subcutaneous adipose tissue and epididymal adipose tissue from High-Fat-Diet induced diabetic rats were investigated before and after rosiglitazone intervention by real time RT-PCR and Western blot analysis respectively.Assay the correlation between monocytes CD36 expression and PPARγ、GLUT4 and other cytokines,metabolic parameters.Results:(1) Similar to Type 2 diabetes metabolic disorder,High-Fat-Diet combined intraperitoneal injection STZ once SD rats appeared evident hyperglycemia,hyperinsulinemia,lipid metabolic disorder and body weight gain.(2) Flow cytometry showed that the MFI of monocytes CD36 expressions in diabetic rats were significantly higher in comparison with controls(P＜0.01).After rosiglitazone intervention the MFI of monocytes CD36 expressions were significantly decreased(P＜0.01).There was a positive correlation between monocytes CD36 MFI and FBG、HOMA-IR.(3) Expressions of CD36 mRNA,PPARγmRNA and their protein in skeletal muscle, subcutaneous adipose tissue and epididymal adipose tissue from diabetic rats were significantly increased and expressions of GLUT4 mRNA and protein in above-mentioned tissues were significantly decreased(P＜0.01).There was a coincidence change between expressions of CD36 and PPARγmRNA or protein. After rosiglitazone intervention,expressions of CD36mRNA,PPARγmRNA and their protein in skeletal muscle were significantly decreased(P＜0.05),expressions of GLUT4 mRNA and protein in skeletal muscle were significantly increased (P＜0.01).Expressions of CD36mRNA,PPARγmRNA,GLUT4 mRNA and their protein in subcutaneous adipose tissue and epididymal adipose tissue were all increased but only in epididymal adipose tissue there was a statistics significance (P＜0.05).(4) The MFI of monocytes CD36 expressions were significantly higher in Type 2 diabetes in comparison with healthy controls(P＜0.01).The MFI of monocytes CD36 expressions in atherosclerosis diabetes were significantly higher in comparison with nonatherosclerosis diabetes(P＜0.01).There was a positive correlation between monocytes CD36 MFI and diabetes duration、FBG、HbA1_C、HOMA-IR.(5) After rosiglitazone intervention,the MFI of monocytes CD36 expressions were significantly decreased in comparison with controls and before rosiglitazone intervention(P＜0.01).The serum levels of sVCAM-1 and TNFαwere significantly decreased(P＜0.01) and the serum levels of adiponectin were significantly increased (P＜0.01).There was a positive correlation between monocytes CD36 MFI and serum levels of sVCAM-1 and TNFα,a inverse correlation between monocytes CD36 MFI and serum levels of adiponectin.Conclusion:High-Fat-Diet combined intraperitoneal injection STZ once SD rats were good Type 2 diabetic rat models.The increased expression of scavenger receptor CD36 in monocytes in the condition of Type 2 diabetes may be one of the mechanism of accelerated atherosclerosis in diabetic,hyperglycemia and insulin resistance were the main up-regulation factors.Rosiglitazone could reduce CD36 expression in monocytes,the mechanism might lie in the good glycaemic control,relief of oxidative stress,improvement of insulin resistance and relief of inflammatory reaction.The expression of CD36 in rat skeletal muscle and adipose tissue was regulated by PPARγand exist tissue specificity.There may be exist different mechanism between subcutaneous adipose tissue and epididymal visceral adipose tissue in insulin resistance,metabolism of lipid and atherosclerosis.更多还原