Wu Jing, Lei Min-xiang, Liu Lan, Xie Xiao-yun
Department of Endocrinology, Xiangya Hospital, Central South University, Changsha 410008, China.
Zhonghua Xin Xue Guan Bing Za Zhi. 2007 Mar;35(3):265-70.
To observe the changes of aortic endothelium-dependent vasodilation function (EDVR) and expressions of endothelial nitric oxide synthase (eNOS), phosphatidylinositol 3-kinase (PI3K), and protein kinase B (PKB) in insulin-resistance (IR) and type 2 diabetic rats.
IR rat model was established by feeding 4-6 week-old male SD rats with high glucose and cholesterol diet for 6 weeks and type 2 diabetes (DM) were induced by intraperitoneal injection with low dose streptozotocin (STZ) to IR rats. Glucose infusion rate (GIR) was determined by euglycemic hyperinsulinemic clamp technique, EDVR by acetylcholine (Ach)-induced vasodilation response in isolated aortic rings, aortic NO concentration by Griess Reaction, activation of eNOS detected by immunohistochemical SP method, mRNA expressions of eNOS-, PI3K- and PKB of aorta were assayed by RT-PCR, aorta ultrastructure observed by electron microscopy. Body weight, fast plasma glucose (FPG), insulin (FINS), triglyceride (TG), cholesterol (TC) were determined and the insulin sensitivity index (ISI) was calculated.
(1) Body weight, FINS, TG and TC levels were significantly higher while ISI and GIR significantly lower in IR and DM rats than that in normal control rats (P < 0.05). (2) Aorta EDVR decreased significantly in IR and DM group compared with that in control group (P < 0.05) and EDVR was also significantly reduced in DM rats than that in IR rats (P < 0.05). The maximum Ach-induced vasodilation response (EDVR(max), P < 0.01) was positively correlated with ISI and negatively correlated with FPG, TG, TC and FINS (P < 0.01). (3) Aortic NO concentration, the mRNA expressions of eNOS-, PI3K-, and PKB and eNOS immunohistochemical expression in aorta were significantly lower in IR and DM rats compared with normal control rats and the decrease was more pronounced in DM rats (P < 0.05 vs. IR). (4) Pathologic aortic ultrastructure changes were also visualized in IR and DM rats.
Our results suggest that reduced NO concentration and expression as well as reduced PI3K-, PKB-, and eNOS mRNA expressions might contributed to the reduced EDVR function and related pathological ultrastructure changes in IR and DM rats.
观察胰岛素抵抗（IR）和2型糖尿病大鼠主动脉内皮依赖性血管舒张功能（EDVR）及内皮型一氧化氮合酶（eNOS）、磷脂酰肌醇3激酶（PI3K）和蛋白激酶B（PKB）表达的变化。
对4 - 6周龄雄性SD大鼠采用高糖高胆固醇饮食喂养6周建立IR大鼠模型，然后对IR大鼠腹腔注射低剂量链脲佐菌素（STZ）诱导2型糖尿病（DM）。通过正常血糖高胰岛素钳夹技术测定葡萄糖输注速率（GIR），采用乙酰胆碱（Ach）诱导离体主动脉环血管舒张反应测定EDVR，用Griess反应检测主动脉NO浓度，用免疫组织化学SP法检测eNOS的激活，用RT - PCR法检测主动脉eNOS、PI3K和PKB的mRNA表达，用电子显微镜观察主动脉超微结构。测定体重、空腹血糖（FPG）、胰岛素（FINS）、甘油三酯（TG）、胆固醇（TC），并计算胰岛素敏感性指数（ISI）。
（1）IR和DM大鼠的体重、FINS、TG和TC水平显著高于正常对照大鼠，而ISI和GIR显著低于正常对照大鼠（P < 0.05）。（2）与对照组相比，IR和DM组主动脉EDVR显著降低（P < 0.05），且DM大鼠的EDVR也显著低于IR大鼠（P < 0.05）。最大Ach诱导的血管舒张反应（EDVR(max)，P < 0.01）与ISI呈正相关，与FPG、TG、TC和FINS呈负相关（P < 0.01）。（3）与正常对照大鼠相比，IR和DM大鼠主动脉NO浓度、eNOS、PI3K和PKB的mRNA表达以及主动脉eNOS免疫组织化学表达显著降低，且DM大鼠的降低更明显（与IR相比，P < 0.05）。（4）IR和DM大鼠主动脉超微结构也出现病理性改变。
我们的结果表明，NO浓度和表达降低以及PI3K、PKB和eNOS mRNA表达降低可能导致IR和DM大鼠EDVR功能降低及相关病理性超微结构改变。
