神经生长因子在糖尿病大鼠视网膜突触可塑性中的作用

Roles of nerve growth factor(NGF) in retinal synaptic plasticity in diabetic rats

目的探讨神经生长因子(nerve growth factors,NGF)在糖尿病大鼠视网膜突触可塑性中的作用。方法取清洁级雄性SD大鼠24只,随机分为对照组、糖尿病组、治疗组,每组8只。后两组采用链脲佐菌素诱导糖尿病模型,模型诱导成功后,治疗组给予腹腔注射鼠NGF(800 U·kg-1),每天1次。对照组、糖尿病组给予等剂量生理盐水。12周后,检测丙二醛(MDA)含量及超氧化物歧化酶(SOD)活性,免疫荧光技术检测视网膜突触素表达,Western blot检测视网膜突触素、Caspase-3的表达。结果3组间MDA含量比较,总体差异有统计学意义(F=85.46,P<0.01);糖尿病组MDA含量较对照组明显升高(P<0.01),治疗组较糖尿病组明显降低(P<0.01)。3组间SOD活性比较,总体差异有统计学意义(F=17.76,P<0.01);糖尿病组SOD活性较对照组明显降低(P<0.01),治疗组较糖尿病组明显升高(P<0.01)。3组间突触素免疫荧光强度比较,总体差异有统计学意义(F=395.42,P<0.01),糖尿病组较对照组荧光强度明显下降(P<0.01),治疗组较糖尿病组荧光强度明显升高(P<0.01)。3组间突触素相对表达量比较,总体差异有统计学意义(F=17.27,P<0.01)。糖尿病组较对照组突触素表达明显减少(P<0.01),治疗组较糖尿病组明显增多(P<0.01)。Caspase-3蛋白相对表达量3组间比较,总体差异有统计学意义(F=217.13,P<0.01)。糖尿病组Caspase-3表达较对照组明显增多(P<0.01),治疗组较糖尿病组明显减少(P<0.01)。结论NGF通过降低糖尿病视网膜氧化应激,抑制了细胞凋亡,恢复了视网膜突触数量。提示NGF可能通过氧化应激途径参与了糖尿病视网膜突触可塑性的变化。

Objective To investigate the effects of nerve growth factor （NGF） on retinal synaptic plasticity of diabetic mellitus rat and its underlying mechanisms. Methods A total of 24 clean SD male rats were randomly divided into three groups （ n = 8 ）, and they were control group, diabetic group and treatment group. In the latter two groups, a model of diabetic rats was induced by streptozotocin, and then the rats of treatment group were injected intraperitoneally 800 U · kg^-1 NGF once a day after the model was induced successfully. Both control group and diabetic group were given the same amount of normal saline. Twelve weeks later, MDA content and SOD activity were detected;meanwhile, the expression of retinal synaptophysin was detected by immuno- fluorescence, and the expressions of retina synaptophysin and Caspase-3 were detected by Western blot. Results The difference of MDA content in the three groups was sta- tistically significant（ F = 85.45 ,P 〈 0.01 ） ; and the content of MDA in the diabetic group was significantly higher than that in the control group （P 〈 0.01 ）, while its content in the treatment group was significantly lower than that in the diabetic group （P 〈 0.01 ）. The difference of SOD activity in the three groups was statistically significant （F = 17.76,P 〈0.01 ） ;and the SOD activity in the diabetic group was significantly lower than that in the control group （P 〈0.01 ） ,while its activity in the treatment group was signif- icantly higher than that in the diabetic group （P 〈0.01 ）. The difference of immunofluo- rescence intensity of synaptophysin in the three groups was statistically significant （F = 395.42 ,P 〈 0.01 ） ;immunofluorescence intensity of synaptophysin in the diabetic group was attenuated compared with the control group （ P 〈 0.01 ）, while the intensity in the treatment group was enhanced compared with the diabetic group（P 〈0.01 ）. The differ- ence of the relative expression of synaptophysin in the three groups was statistically sig- nificant（F = 17.27 ,P 〈 0.01 ） ;and the expression of synaptophysin in the diabetic group was significantly downregulated compared with the control group （P 〈 0.01 ）, while its expression in the treatment group was upregulated compared with the diabetic group （P〈0. 01 ）. The difference of relative expression of Caspase 3 protein in the threegroups was statistically significant （F = 217.13 ,P 〈0.01 ） ;and the expression level of Caspase 3 in the diabetic group was significantly higher than that in the control group （P 〈 0.01 ）, while its level in the treatment group was significantly lower than that in the diabetic group （P 〈 0.01 ）. Conclusion NGF can help to inhibit the apoptosis of retinal cell, restore the number of retina synapse by reducing the oxidative stress in diabetic retina, which suggests that NGF may be involved in the changes of synaptic plasticity in diabetic retina via oxidative stress pathway.