叶酸对2型糖尿病大鼠胸主动脉内皮功能的影响

目的探讨长期补充叶酸对2型糖尿病大鼠胸主动脉内皮功能的影响及其作用机制。方法将2型糖尿病大鼠37只分为模型组(12只)、小剂量叶酸组(12只)和大剂量叶酸组(13只),另11只正常大鼠为正常对照组,叶酸干预11周后,剪尾采血分别检测血清一氧化氮、超氧化物歧化酶及丙二醛水平,并取胸主动脉制备主动脉环进行离体血管环反应性测定。结果模型组大鼠血清一氧化氮和超氧化物歧化酶水平明显低于正常对照组(P<0.01),而血清丙二醛水平明显高于正常对照组(P<0.01);补充叶酸11周后,小剂量叶酸组及大剂量叶酸组血清一氧化氮及超氧化物歧化酶水平均较模型组有明显增高(P<0.05或P<0.01),而血清丙二醛水平较模型组明显降低(P<0.01)。在每一个乙酰胆碱累积浓度下,模型组大鼠胸主动脉环的舒张度均较正常对照组明显减低(P<0.05或P<0.01),而小剂量叶酸组和大剂量叶酸组大鼠胸主动脉环的舒张度则均较模型组明显增高(P<0.05或P<0.01),小剂量叶酸组大鼠胸主动脉环的舒张度与大剂量叶酸组相比差异无显著性。结论长期补充叶酸对2型糖尿病大鼠血管内皮功能损伤具有明显预防作用,叶酸可能通过增加机体一氧化氮合成从而提高血清一氧化氮活性和提高机体抗氧化能力来预防2型糖尿病大鼠血管内皮功能损伤的发生。

Effects of Folate on Endothelial Function of Thoracic Aortea in Rats with Type 2 Diabetes Mellitus

Aim To investigate the effect of long-term folate supplementation on endothelial function of thoracic aortea in rats with type 2 diabetes mellitus and explore its mechanisms.Methods After the rat model of type 2 diabetes mellitus was established by a single injection of low dose streptozotocin(STZ)after 6 weeks of high calorie diet,the animals were divided into model group,low-dose folate group and high-dose folate group.Other 11 rats were employed as normal control group.The levels of nitric oxide(NO),superoxide dismutase(SOD)and maleic dialdehyde(MDA)in the serum were determined.Acetylcholine-induced endothelium-dependent vascular relaxation(EDVR)of aorta rings was tested.Results The levels of NO and SOD in serum were significantly lower and the level of MDA in serum was notably higher in model group than those in normal control group;After 11 weeks of folate supplementation,compared with model group,the levels of NO and SOD in serum significantly increased in low-dose folate group and high-dose folate group,while the level of MDA in serum decreased markedly.Compared with normal control group,EDVR responses to acetylcholine(Ach)of each concentration were obviously weakened in model group.Compared with model group,EDVR responses to Ach of each concentration were significantly improved in low-dose folate group and high-dose folate group,and further increment of folate led to no further improvement of EDVR response.Conclusion Long-term folate supplementation can effectively prevent the EDVR impairment.The effect may be associated with the increase of NO formation and its antioxidant effect.