The Pathological Changes Of Retina Of Diabetic Rats And Its Expression Of VEGF And PEDF In Different Times

Objective: To observe pathologic changes of retina of diabetic rats indifferent period, and to research the dynamic expression of VEGF and PEDFin retina. In order to explore the pathological changes of retina in the development of diabetes and discuss the significance of expression of VEGF and PEDF in the development of diabetic retinopathy.Method:123male SD rats were divided randomly into the first month normal control group (CON1group),the third month normal control group (CON2group),the fifth month normal control group(CON3group),the first month diabetic groups(DM1group),the third month diabetic group(DM2group),the fifth month diabetic group(DM3group).The rats in three diabetic groups wereinduced to diabetic animal models through intraperitoneal injection of streptozotocin(STZ). After the models established successfully,the pathologicchanges of retina were investigated through transmission electron microscope,HE staining, retinal stretched preparation with Evans blue(EB) and retinal EB contant caculation.In additon,VEGF and PEDF expression in retina were caculated through immunohistochemistry,real-time PCR and Western-blot.Results: The ultrastructure of retinal cells of diabetic rats had changed in initial peroid of diabete,and was aggravating as the disease progresse,HE staining showed the pathologic changes of retina were aggravating as the disease progresse as well.The retinal stretched preparation with EB show ed that the vascular morphology of CON group was normal,and the retinal blood vessels of DM1group was almost normal,which was compared with the CONgroup.The retinal vascular of DM2group was tortuous,and part of the morphology of vascular was changed, with a small amount of fluorescein leakage.The retinal vascular became highly irregular and had a lot of leakage of fluoresced in DM3group. The EB contant in retinal increased with disease aggravating,retinal EB contant of DM1group,DM2group,and DM3group were15.786±1.848（ng/mg）、21.596±1.922（ng/mg）、26.310±2.179（ng/mg,and the data had statistical significant(P<0.05). The immunohistochemistry showed that with disease aggravated, intensity of positive staining of VEGF increased butwhich decreased of PEDF. MOD of VEGF in CON1group，CON2group,CON3group,DM1group,DM2group and DM3group were0.215±0.019、0.225±0.024、0.215±0.021、0.302±0.031、0.523±0.047、0.748±0.078;MOD of PEDF in which were0.908±0.073、0.915±0.031、0.898±0.029、0.735±0.087、0.607±0.055、0.187±0.039, and the data had statistical significant(P<0.05).The relative quantitative expression of VEGF in CON1group，CON2group,CON3group,DM1group,DM2group and DM3group in real-time PCR were0.105±0.014、0.099±0.129、0.106±0.012、0.372±0.037、1.031±0.095、2.364±0.198; The relative quantitative expression of PEDF were2.643±0.188、2.589±0.136、2.533±0.1521.528±0.093、0.905.±0.111、0.254±0.077. Western-blot show that the expression of VEGF inCON1group，CON2group,CON3group,DM1group,DM2group and DM3group were0.328±0.028、0.317±0.048、0.331±0.035、0.436±0.034、0.651±0.028、0.793±0.026;the expression of PEDF were0.796±0.063、0.802±0.034、0.799±0.041、0.605±0.086、0.424±0.065、0.263±0.067.In addition, the data among all the groups in the method above were statistical significant (P<0.05).Conclusion:1. The retinal cells of diabetic rats had occurred pathological changes in the early course of diabete,and aggravating with the diseaseprogressing;2. Morphological changes of retinal vascular of diabetic rat occuredlate in the course of the disease, and aggravated with the disease progressing;3. The function of blood-retinal barrier was disrupted in early of diabete andaggravated with the disease developing;4.The imbalance of retinal VEGF and PEDFexpression existed in early course of diabetes, with the progression of thedisease, VEGF expression increased but PEDF expression reduced. The imbalanceof VEGF and PEDF expression in diabetic retina was throughout the developmentof diabetes.