Effects of puerarin on the retina and STAT3 expression in diabetic rats

The effects of puerarin on electroretinogram, oxidative stress and STAT3 expression were determined, in diabetic rat retina and serum. Forty Sprague-Dawley rats were randomly divided into the normal control (NC), the diabetic model (DM), the low dose (250 mg/kg) puerarin (LP) or the high dose (500 mg/kg) puerarin group (HP). A diabetic rat model was induced by streptozotocin and animals were continuously treated for 4 weeks; fasting blood glucose was measured at 2 and 4 weeks after modeling. An electroretinogram and serum and tissue levels of glucose, insulin, superoxide dismutase (SOD), malondialdehyde (MDA) and total antioxidant capacity (T-AOC) were measured; real-time PCR and ELISA were used to determine STAT3 mRNA and protein expression, respectively, from the retina. The blood glucose and insulin levels in the puerarin groups were significantly lower and higher, respectively than that in the DM group. The amplitude of b-wave of electroretinogram in the DM and the LP groups was significantly lower than that in the NC group; in the LP and HP groups it was significantly higher than the DM group. The serum and retinal tissue activity of SOD and MDA was significantly lower and higher, respectively, in the DM group compared to the NC group; both the LP and HP groups had significantly higher SOD and lower MDA than the DM group. The levels of STAT3 mRNA and protein levels in the DM, LP and HP groups were significantly higher than the NC group; and levels of STAT3 mRNA and protein expression were significantly lower in the LP and HP groups than the DM group. In summary, puerarin can reduce the oxidative stress damage of the retina, and its mechanism is related to the inhibition of STAT3 expression.