Effect of a combination of carnosine and aspirin eye drops on streptozotocin-induced diabetic cataract in rats

Purpose: To investigate the effect of a combination of carnosine and aspirin eye drops on the progression of diabetic cataract formation induced by streptozotocin (STZ). Methods: Rats were made diabetic with STZ. Animals in the treated groups received carnosine, aspirin, or a combination of carnosine and aspirin as drops to the eyes. Cataract progression was monitored by slit lamp microscope and classified into four stages. At the end of 8 weeks, the animals were killed and biochemical changes were determined. Blood and urine glucose levels, body weights, food, and intake were also determined. Results: About 84.4% of the rats responded to the STZ injection. There were statistically significant differences in the stage of cataract of lenses between the untreated and the treated diabetic animals and between the combination and the aspirin group at the 7th and 8th week. There was a significant decrease in the water-soluble protein in the diabetic groups compared with the control group. The three treatments improved the water-soluble protein levels, and the combination treatment had the greatest effect. The levels of thiol were remarkably decreased in the lenses of diabetic rats, except the combination group. The specific activity of glutathione peroxidase (GPx) was increased and the activities of glutathione reductase (GR) and catalase (CAT) were decreased in all the diabetic groups. Conclusions: The results indicated that carnosine, aspirin, and a combination eye drops are effective against the onset and development of diabetic cataract in rats. Most important, the effect of combination eye drops is better than aspirin only.