牛磺酸对链脲佐菌素诱导的糖尿病幼鼠氧化应激系统及早期血管内皮损伤的干预性研究

Effects of early intervention with taurine on oxLDL/LOX-1 system and vascular endothelial dysfunction in young streptozotocin-induced diabetic rats

目的观察牛磺酸对糖尿病幼鼠氧化应激系统（oxLDL／LOX-1）的影响及早期血管内皮损伤的干预作用，探讨其可能的分子机制。方法6周龄Wistar雄性大鼠30只随机取出8只作为正常对照组，其余给予链脲佐菌素（60mg／kg）一次性腹腔注射诱导1型糖尿病模型，造模成功后随机各取8只分为糖尿病未干预组和糖尿病牛磺酸干预组（每日饮水中加入1％牛磺酸）。干预4周后处死大鼠，检测大鼠外周血血糖、甘油三酯（TG）、总胆固醇（TC）、低密度脂蛋白（LDL）、高密度脂蛋白（HDL）、氧化低密度脂蛋白（oxLDL）及可溶性细胞间黏附分子1（sICAM-1）；采用免疫组织化学法、免疫印迹和逆转录一聚合酶链反应法，分别检测腹主动脉壁血凝素样氧化低密度脂蛋白受体1（LOX-1）和细胞间黏附分子1（ICAM-1）蛋白及基因表达水平。结果糖尿病未干预组外周血TG、TC、LDL及oxLDL、sICAM-1水平均高于正常对照组（P均〈0．01）；腹主动脉壁LOX—1和ICAM-1的蛋白及基因表达水平亦明显高于正常对照组（P均〈0．01）；糖尿病牛磺酸干预组较糖尿病未干预组外周血TG（0．64±0．12与0．97±0．18）、TC（0．82±0．18与1．01±0．23）、oxLDL（3．1±0．6与4．2±0．6）、sICAM-1（108．3±18．0与130．7±17．4）水平和腹主动脉壁LOX．1、ICAM-1蛋白（1．02±0．19与2．60±0．33，1．21±0．22与2．98±0．31）及基因表达水平（0．45±0．09与0．96±0．15，0．50±0．07与0．87±0．16）均明显下降（P均〈0．05）。LOX-1的蛋白表达水平与血清oxLDL（r=0．922，P=0．001）、sICAM-1（r=0．753，P=0．031）以及腹主动脉ICAM-1（r=0．849，P=0．008）的蛋白表达水平均呈正相关。结论糖尿病幼鼠存在血管内皮细胞功能损伤，牛磺酸早期干预对糖尿病幼鼠血管内皮具有保护作用。

Objective As an endogenous antioxidant, taurine could retard the development of diabetic cardiovascular complications. Whereas, whether TAU has a protective effect on diabetic vascular endothelium in young patients is still unclear. This study aimed to investigate the protective effect of taurine on early vascular endothelial dysfunction and its possible mechanism by detecting the changes of oxLDL/ LOX-1 system in young STZ-induced diabetic rats. Doing so, the authors expect to find an effective approach in clinical practice to the prevention and treatment of diabetic vascular complication. Method Six-week-old rats were divided randomly into normal control （ CN group, n = 8 ）, diabetes mellitus group （ DM group, n = 8） and taurine supplement group （DM ＋ TAU group, n = 8） . Diabetes was induced in the rats by intraperitoneal injection of streptozotocin （ STZ, 60 mg/kg） and after the onset of diabetes, the rats in DM ＋ TAU group were given free access to drinking water containing 1% taurine. At the end of 4 weeks, blood glucose, serum total cholesterol （TC）, triglyceride （TG）, low-density lipoprotein （LDL） and high-density lipoprotein （HDL）, oxidized low density lipoprotein （oxLDL） and sICAM-1 levels were determined, meanwhile LOX-1 and ICAM-1 expression on abdominal aortas were examined by immunostaining, Western blotting and reverse transcription PCR, respectively. The results were quantified by densitometry. Result Compared to normal control,in STZ-induced diabetic rats, the levels of serum TC, TG, LDL, oxLDL and sICAM-1 were all increased （ P 〈 0. 01 for all）, meanwhile LOX-1 and ICAM-1 expression （ protein and mRNA） in the endothelium layers of abdominal aortas were also markedly enhanced （P 〈 0. 01 for all）; while in taurine supplemented rats, the levels of serum TG （0. 64 ±0. 12 vs. 0. 97 ±0. 18） , TC （0. 82 ± 0.18vs. 1.01±0.23）, oxLDL （3.1±0.6 vs. 4.2±0.6）, sICAM-1 （108.3±18.0 vs. 130.7 ±17.4）, expression of LOX-1 and ICAM-1 protein （1.02±0. 19 vs. 2. 60 ±0. 33, 1.21 ±0. 22 vs. 2. 98±0. 31） as well as mRNA （0.45 ±0. 09 vs. 0. 96 ±0. 15, 0. 50 ±0. 07 vs.0. 87 ±0. 16） were all markedly lower than those of untreated diabetic rats （ P 〈 0. 05 for all ）. Also, the level of LOX-1 protein expression was positively correlated with levels of serum oxLDL （ r = 0. 922, P = 0. 001 ） , sICAM-1 （ r = 0. 753, P = 0. 031） and ICAM-1 expression on abdominal aorta （r = 0. 849, P = 0. 008）. Conclusion Vascular endothelial dysfunction was present in early stage of young diabetic rats and taurine supplement could protect against this early endothelial dysfunction by its antioxidation to inhibit the role of oxLDL/LOX-1 system in young rats with diabetes mellitus.