丝胶对Ⅱ型糖尿病大鼠海马生长激素／胰岛素样生长因子-1轴的作用

Effects of sericin on growth hormone/insulin-like growth factor-1 axis of the hippocampus in type 2 diabetes mellitus rat

目的：探讨丝胶对Ⅱ型糖尿病大鼠海马生长激素（GH）／胰岛素样生长因子-1（IGF-1）轴的作用。方法：雄性SD大鼠随机分为正常对照组、糖尿病模型组、丝胶治疗组和阳性对照组。2％链脲佐菌素3d连续腹腔注射的方法建立Ⅱ型糖尿病大鼠模型后，丝胶治疗组和阳性对照组大鼠分别给予丝胶和二甲双胍灌胃治疗35d。ELISA法检测各组大鼠血清GH和IGF-1水平，免疫印迹和RT-PCR法分别检测大鼠海马GH、生长激素受体（GHR）和IGF-1蛋白和mRNA的表达。结果：与正常对照组大鼠比较，糖尿病模型大鼠血清GH水平、海马GH的表达明显升高，血清IGF-1水平、海马GHR和IGF-1的表达明显降低；与糖尿病模型组大鼠比较，丝胶治疗组大鼠血清GH水平、海马GH的表达明显降低，血清IGF-1水平、海马GHR和IGF-1的表达明显升高。结论：丝胶可通过调节糖尿病海马GH／IGF-1轴的异常变化减轻海马损伤。

Objective： To investigate the effects of sericin on growth hormone （GH）/insulin-like growth factor-1（IGF-1） axis of the hippocampus of type 2 diabetes mellitus rats. Methods： Male SD rats were randomly divided into 4 groups： a normal control group, a diabetes model group, a sericin treatment group and a positive control group. The type 2 rat model was established by peritoneal injection of small dose streptozotocin continuously. Then the rats in the sericin treatment group and positive group were respectively lavaged with sericin and metformin for 35 days. ELISA was used to detect GH and IGF-1 level in the serum of the rats in each group, and Western blotting and RT-PCR to detect GH, growth hormone receptor （GHR）, IGF-1 protein and mRNA expression in the hippocampus. Results： Compared with the rats in the normal control group, the GH level in serum and GH expression in the hippocampus of the rats in the diabetes model group increased obviously; IGF-1 level in serum, GHR and IGF-1 expression in the hippocampus decreased obviously. Compared with the diabetes model rats, the GH level in the serum and GH expression in the hippocampus of the rats in the sericin treatment group decreased significantly; The IGF-1 level in serum, GHR and IGF-1 expression in the hippocampus increased obviously. Conclusion： Sericin can reduce hippocampus injury during diabetes by regulating abnormal variation of GH/IGF-1 axis.