Attenuation and delay of diabetic cataracts by antioxidants: effectiveness of pyruvate after onset of cataract.

Cataract is one of the most significant vision-impairing complications of diabetes. The present study examined the feasibility of inhibiting cataract formation by treatment with pyruvate, a metabolite known to effectively scavenge reactive species of oxygen and inhibit protein glycation, both known to be involved in the genesis of diabetic cataracts. In addition, pyruvate stimulates tissue metabolism, which is depressed with the onset of cataract formation. The objective of our experiments was to determine if this compound could be effective in offsetting the progress of cataract, specifically if administered after the diabetes-induced lens changes have begun, as opposed to the previous reports wherein it has been reported to delay cataract formation if administered prophylactically with the immediate onset of diabetes. Diabetes was induced by intraperitoneal administration of streptozotocin to mice. Lens transparency was assessed by slit lamp examination and its photography. ATP was determined enzymatically by reacting it with luciferin-luciferase mixture and measuring the fluorescence intensity. The findings described herein are in accordance with this possibility. The incidence of cataract in the group of diabetic animals, where treatment with pyruvate was initiated after the initial lens changes set in, was significantly lower at all times of observation in comparison to the untreated diabetic group. In addition, the severity of opacities in the pyruvate-treated group, when present, was much minor, the transparency of these cases being close to that in the control animals. The ophthalmic findings are supported biochemically by ATP levels, which were significantly higher in the pyruvate group in comparison to the untreated group. The present findings emphasize the clinical usefulness of initiating treatment with anti-oxidants and metabolic agonists even when the lens changes are detected at the time of the diabetes diagnosis. The latter usually comes much later than the onset of visual aberrations. Prophylaxis is not an absolute requirement.