Research Of Protective Effect Of Pyruvate Sodium On Diabetic Retinopathy Of Rat

Diabetic Retinopathy (DR) is a common complication of diabetes mellitus and is one of the severe eye diseases leading to blindness which involves more and more younger patients as the incidence of the disease increasingly. But the mechanisms of DR remain unclear so that DR lacks effective therapy in early stage. Recently the importance of pyruvate has been noticed in glucose metabolism because of its special antioxidative effects. Previous researches have proved that pyruvate sodium (NaPyr) have obvious therapeutic effects on diseases related to oxidative damage such as diabetic cataract, myocardial ischemia and ischemic central nervous system. It can be inferred that NaPyr may also have effect on DR. Our study used diabetic rat model evoked by intraperitoneal injection with streptozotocin (STZ). The protective effects of NaPyr on early stage DR rats'Miiller cells were evaluated by biochemistry, immunofluorescence and observation of cell ultrastructure by using electron microscope.Objective To investigate protective effect of NaPyr on diabetic retinopathy.Methods The SD rat model of diabetic retinopathy was built by injection of STZ (75mg/kg). The rats were divided into diabetic control, oral and injection groups. Rats in oral group were fed with 2% NaPyr, while rats in injection group received 250mg/kg NaPyr in sterilized equilibrium solution weekly by intraperitoneal injection every other day. Rats in diabetic control group received the same volume of sterilized saline every other day. Rats were sacrificed and then their retinal tissues were taken for biochemistry examination for MDA by thiobarbituric acid test and SOD by xanthine oxidase test respectively after 1, 4,6 months. Expression and distribution of GS and GFAP was also measured by immunofluorescence. Ultrastructure of retina was evaluated by electron microscopy.Results One month after models were established, the level of MDA was much higher in control and oral groups than in injection group, the difference was statistically significant (P<0.001). There was no difference in MDA levels among each group (P>0.05) after 4 months. One month after the models were established, the level of SOD was no difference among each group (P>0.05). After 4 months, the SOD level in oral and injection groups was higher than in control group (P<0.05). After 6 months, the level of SOD was no difference among each group (P>0.05). The research about Muller cells discovered that area of staining of GS remained the same among each groups. But area of staining of GFAP was significantly reduced after 1 month and 4 months in oral and injection groups than diabetic control group. The ultrastructure of Miiller cells and ganglion cells in oral and injection groups was less changed than control group after 1 month. After 4 months, the ultrastructure of Muller cells and ganglion cells was destroyed in each group. But the ultrastructure of Muller cells and ganglion cells in oral groups was less destroyed in oral group than in control and injection groups.Conclusion In the early period of diabetic retinopathy, NaPyr may be an effective protective therapy. But with the development of the disease, more researches about NaPyr are needed to prove it.