Expression of ERK and c-fos and effect of brain derived neurotrophic factor in early retinal neuropathy of streptozotocin-induced diabetes in rat / 中华实验眼科杂志

ABSTRACT

BackgroundRecent studies showed that diabetic retinal neuropathy is an earlier and more dangerous complication and neurotrophin has a protective effect on retina.ObjectiveThe present study was to observe the changes of brain derived neurotrophic factor (BDNF),its receptor TrkB,signal pathway protein phosphatized extracellular signal-regulated protein kinase1/2 (p-ERK1/2) and c-fos in the retina after injection of BDNF into the vitreous in STZ induced Wistar diabetic rats.MethodsWistar rats aged 9 weeks-old were randomly divided into BDNF injection group,diabetes mellitus (DM) control group and normal control group and 20 rats for each group.STZ was intraperitoneally injected in the rats of BDNF injection group and DM control group to create the experimental DM.BDNF was intravitreously injected in the rats of BDNF group 2 weeks after administration of STZ in three-day interval for 5 times,and BSS containing O.1％ bovine serum albumin (BSA) was used at the same way in the DM control group and normal control group.The retina was isolated for hybridization in situ for BDNF,and TrkB,p-ERK1/2 and c-fos.Levels in retina were detected using sandwich method ELISA.ResultsThe number of BDNF positive cells and the gray scale were lower obviously in the rat retina of DM control group than those of BDNF injection group and normal control group,showing significant differences among the 3 groups ( F =102.36,92.55 ;P＜0.05 ).ELISA assay showed that TrkB,p-ERK1/2 and c-fos values in retina were statistically significantly different among the 3 groups ( F =92.54,95.46,94.84,P＜0.05 ).The TrkB level in retina was statistically reduced,but the p-ERK1/2 and c-fos levels in retina were increased statistically in DM control group compared with BDNF injection group and normal control group( P＜0.05 ).No statistical difference was found in TrkB,p-ERK1/2 and c-fos values between the BDNF injection group and normal control group(P＞0.05).ConclusionsThe injection of BDNF into the vitreous cavity can protect retina from downregulating BDNF and TrkB levels and up-regulating the p-ERK1/2 and c-fos protein levels in the early stage of DM.