丝胶对糖尿病大鼠海马一氧化氮含量及一氧化氮合酶表达的影响

摘要

Objective To investigate the effects of color silk cocoon extraction-sericin on nitric oxide (NO) content and neuronal nitric oxide synthase (nNOS) expression in hippocampus of diabetes mellitus (DM) rats. Methods 48 male SD rats were randomly divided into 4 groups (n = 12): normal control, DM model, sericin and mefformin groups. The rats in model, sericin and metformin groups were all established DM rats model by intraperitoneally injected streptozotocin; blood glucose ≥16. 7 mmol/L was taken as standard to judge if the rats model were successfully established. After DM modelS were successfully established, the rats in sericin and metformin groups were re spectively lavaged with sericin ( 2. 4 g · kg -1 · d-1 ) and metformin (55.33 mg · kg-1 · d-1 ) for 35 days. Morris water maze was used to detect space learning and memory ability of rats in each group; immunohistochemical staining to observe nNOS expression in neurons of hippocampus; nitrate reductase method to detect NO content in hippocampus. Results Compared with normal control rats: space learning and memory ability of DM model rats decreased obviously, nNOS expression in neurons of hippocampus and NO content in hippocampus raised significantly ( P ＜0. 05, P ＜0. 01 ). Compared with DM model rats: space learning and memory ability of rats in sericin group and metformin group increased obviously, nNOS expression in neurons of hippocampus and NO content in hippocampus decreased significantly ( P ＜ 0. 05,P ＜0. 01 ); Moreover, there was no obvious differences between sericin group and metformin group ( P ＞0. 05 ). Conclusions Sericin can effectively raise learning and memory ability and obviously improve cognitive dysfunction of DM rats through lightening toxicity of excess NO to hippocampal neurons.%目的 观察彩色蚕茧提取物.丝胶对糖尿病大鼠海马一氧化氮(NO)含量和一氧化氮合酶(NOS)表达的影响.方法 48只雄性SD大鼠随机分为4组,正常对照组、糖尿病模型组、丝胶组和二甲双胍组,每组12只.模型组、丝胶组和二甲双胍组大鼠均采用2%链脲佐菌素连续腹腔注射建立糖尿病动物模型,以血糖≥16.7 mmol/L作为成模标准.待模型成功建立后,丝胶组和二甲双胍组大鼠分别给予丝胶(2.4 g·kg-1·d-1)和二甲双胍(55.33 mg·kg-1·d-1)灌胃,连续35 d.采用Morris水迷宫实验检测各组大鼠的空间学习记忆能力,免疫组化染色观察海马神经元神经型一氧化氮合酶(nNOS)的表达,硝酸还原酶法检测海马NO的含量.结果 与正常大鼠比较:糖尿病模型大鼠的空间学习记忆能力明显下降.海马神经元nNOS的表达以及海马NO的含量明显升高(P<0.05,P<0.01).与糖尿病模型大鼠比较:丝胶组和二甲双胍组大鼠的空间学习记忆能力明显提高,海马神经元nNOS的表达以及海马NO的含量明显降低(P<0.05,P<0.01);且丝胶组与二甲双胍组比较无明显差异(P>0.05).结论 丝胶可通过减轻糖尿病时过量NO对海马神经元的毒性提高糖尿病大鼠的学习记忆能力,从而改善糖尿病时的认知功能障碍.