Peroxynitrite-induced formation of diabetic cataract and its prevention by puerarin in rat

Abstract

To investigate the effect of peroxynitrite on the formation of diabetic cataract and its reversal by puerarin. in rat. Normal Sprague-Dawley (SD) rats were equally divided into control group, streptozotocin group (STZ) and treatment group. STZ and treatment group were treated with STZ to establish animal model of diabetic rat cataract and in treatment group puerarin was given by peritoneal injection. General condition and lens shape of rats were examined at 20th, 40th, 60th day respectively. Lens epithelial cells (LEC) were observed with optical microscope. percentage of apoptotic cells, and fluorescent intensity of positive cells for nitrotyrosine (NT) which is the symbol of peroxynitrite were tested by flow cytometry. The expression of NT in the lens was analyzed by Western blot analysis. On 20th, 40th, 60th day of the experiment, clear, mild and severe lens opacity were found in control group, treatment group, and STZ group respectively and the lens opacity was gradually increased in all of rats included in the study. Under optical microscope, no changes were presented in control group, but mild changes were showed in treatment group and remarkable changes were found in STZ group. On all the specified days, distinguishable differences were found in the amount and percentage of apoptotic cells compared with that of control group in treatment group and STZ groups as well as between treatment and STZ groups (P < 0.05). There was significant increase in the fluorescent intensity and amount of NT in treatment and STZ groups compared with that of control group (P < 0.05), and the similar results were revealed between treatment group and STZ. The amount of expression of NT protein at different time points in different groups as described above was also significant difference (P < 0.001). Peroxynitrite plays an important role in the formation of diabetic rat cataract and is a participant in the pathogenesis of oxidative stress induced cataract. Puerarin is an effective antioxidative agent in the treatment of early diabetic rat cataract.