Prevention of cataract in diabetic mice by topical pyruvate

BACKGROUND It has been previously reported that oral administration of sodium pyruvate inhibits oxidative stress and cataract formation in diabetic animals. With a view to exploring the clinical usefulness of these findings, this study examined its preventive effect when administered topically as an eye drop. METHODS Diabetes was induced by intraperitoneal injections of streptozotocin. At the onset of diabetes, an eye drop preparation containing 2.5% sodium pyruvate was administered six times a day at 90-minute intervals. Treatment was continued for 6 weeks. Cataract formation was monitored ophthalmoscopically after mydriasis with 1% tropicamide eye drops. Subsequently, the treated and untreated diabetic animals and the age-matched normal controls were euthanized, their eyes enucleated, and the lenses isolated for biochemical assessment of protein glycation and glutathione levels. RESULTS Treatment with pyruvate eye drops was found to be significantly effective in inhibiting protein glycation. Glutathione levels were also better maintained. In addition, ophthalmoscopic examination revealed that the incidence of cataract in the pyruvate-treated group was only 12% as compared with the untreated diabetics in whom the incidence was 73%. Cataracts at this stage were largely equatorial. CONCLUSION The results demonstrate that topical application of pyruvate can potentially be useful in attenuating or preventing cataract formation induced by diabetes and other conditions of oxidative stress.