[Effect of pyruvate on polyol pathway and lens epithelium apoptosis in diabetic rats]

To investigate the effect of polyol pathway on the lens epithelium apoptosis and caspase-3 activity and its reversal by pyruvate in diabetic rats.

Two hundred and twenty Wistar rats were divided into 3 groups: control group (60 rats), experiment group (80 rats) and treatment group (80 rats). After streptozotocin (STZ) induced cataract, the treatment group received 2% pyruvate in the diet and drinking. Lens opacification was detected by microscope every 2 weeks. Amounts of glucose and sorbitol in the lens were quantified by high-performance liquid chromatography 4, 8 and 12 weeks after the treatment. The percentage of lens epithelium undergoing apoptosis was measured by Annexin V-PI staining. The activity of caspase-3 was analyzed by Western-blot.

Present study showed that there was significant increase of glucose and sorbitol in the lens in the experiment group, the apoptosis rate and caspase-3 activity of lens epithelium were also gradually increased. Pyruvate treatment decreased the levels of sorbitol, glucose, lens epithelium apoptosis and caspase-3 activity. The progress of cataract was also significantly delayed.

Activation of polyol pathway, possibly through regulation of the activity of caspase-3, can induce apoptosis of the lens epithelium. Pyruvate ingested orally can effectively inhibit diabetic cataractogenesis in rats through inhibit polyol pathway.