Protective effect of glycine in streptozotocin-induced diabetic cataract through aldose reductase inhibitory activity.

Glycine is a proteinogenic amino acid that serves as a precursor for several proteins. The anti-cataract effects of lysine and other amino acid mixtures in animal models have been reported. Normal rats were administered saline and formed the normal control group (group I). Diabetic rats were administered streptozotocin and were the diabetic control group (group II). Rats were administered glycine (250 mg and 500 mg/kg of body weight) formed groups III and IV, respectively. Diabetic rats were administered sorbinil and were served as positive control (group V). The body weight changes, serum glucose, plasma insulin, total protein, glutathione (GSH) content, and mRNA and protein levels of aldose reductase were determined. Glycine treatment increased body weight gain, reduced blood glucose, and increased plasma insulin levels compared to diabetic control rats, and also increased GSH content and decreased mRNA and protein levels of aldose reductase compared to their respective controls. In summary, glycine supplementation effectively inhibited aldose reductase enzyme activity in experimental diabetic rats.