Aim: This study was performed to determine the effect of caffeic acid phenethyl ester (CAPE) treatment on levels of malondialdehyde (MDA) and nitric oxide (NO) and activities of antioxidant enzymes in retinas of streptozotocin (STZ)-induced diabetic rats. Materials and Methods: Twenty-seven rats were enrolled and divided into three groups: group 1: non-diabetic rats as control (n = 9); group 2: STZ-induced, untreated diabetic rats (n = 8); and group 3: STZ-induced, CAPE-treated diabetic rats (n = 10). Levels of MDA and NO and the activities of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) in retinal tissues were analyzed. Results: In retinas of untreated diabetic rats, levels of MDA and NO and the activity of GSH-Px were significantly increased (P = 0.001, P = 0.0001, P = 0.0001, respectively), while the SOD activity was significantly decreased (P = 0.021) when compared to the control group. GSH-Px activity in the CAPE-treated diabetic group was markedly higher than that of the control group (P = 0.0001). MDA and NO levels were lower (P = 0.005, P = 0.001, respectively) and SOD activity was higher in the CAPE-treated diabetic group compared to the untreated diabetic group (P = 0.016). Conclusions: It can be concluded that nitrosative and oxidative stress is increased in the diabetic retina. CAPE treatment inhibits lipid peroxidation and NO overproduction and regulates SOD enzyme activities in diabetic rat retinas while it has no effects on GSH-Px activity.

Aim: This study was performed to determine the effect of caffeic acid phenethyl ester (CAPE) treatment on levels of malondialdehyde (MDA) and nitric oxide (NO) and activities of antioxidant enzymes in retinas of streptozotocin (STZ)-induced diabetic rats. Materials and Methods: Twenty-seven rats were enrolled and divided into three groups: group 1: non-diabetic rats as control (n = 9); group 2: STZ-induced, untreated diabetic rats (n = 8); and group 3: STZ-induced, CAPE-treated diabetic rats (n = 10). Levels of MDA and NO and the activities of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) in retinal tissues were analyzed. Results: In retinas of untreated diabetic rats, levels of MDA and NO and the activity of GSH-Px were significantly increased (P = 0.001, P = 0.0001, P = 0.0001, respectively), while the SOD activity was significantly decreased (P = 0.021) when compared to the control group. GSH-Px activity in the CAPE-treated diabetic group was markedly higher than that of the control group (P = 0.0001). MDA and NO levels were lower (P = 0.005, P = 0.001, respectively) and SOD activity was higher in the CAPE-treated diabetic group compared to the untreated diabetic group (P = 0.016). Conclusions: It can be concluded that nitrosative and oxidative stress is increased in the diabetic retina. CAPE treatment inhibits lipid peroxidation and NO overproduction and regulates SOD enzyme activities in diabetic rat retinas while it has no effects on GSH-Px activity.