Roles of nerve growth factor (NGF) in retinal synaptic plasticity in diabetic rats / 眼科新进展

ABSTRACT

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 immunofluorescence,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 statistically significant (F =85.46,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 significantly higher than that in the diabetic group (P ＜0.01).The difference of immunofluorescence 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 difference of the relative expression of synaptophysin in the three groups was statistically significant (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 three groups 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.