Cataract development in diabetic sand rats treated with alpha-lipoic acid and its gamma-linolenic acid conjugate

Background Diabetes commonly leads to long-term complications such as catar act. This study investigated the effects of alpha -lipoic acid (LPA) and it s gamma -linolenic acid (GLA) conjugate on cataract development in diabetic sand rats. Methods Two separate experiments were conducted. In Experiment 1, sand rats were fed a 'high-energy' diet (70% starch), an acute model of Type 2 diabe tes, and injected with LPA. In Experiment 2, the animals received a 'medium -energy' diet (59% starch), a chronic diabetic model, and were intubated wi th LPA or its GLA conjugate. Throughout the experiments, blood glucose leve ls and cataract development were measured. At the termination of the experi ments, lens aldose reductase (AR) activity and lenticular reduced glutathio ne (GSH) levels were analyzed. Results LPA injection significantly inhibited cataract development and redu ced blood glucose levels in rats fed the 'high-energy' diet. Lens AR activi ty tended to be lower, while lenticular GSH levels increased. In sand rats fed a 'medium-energy' diet (59% starch), LPA intubation had no effect on bl ood glucose levels and cataract development but GSH levels were increased. In contrast, sand rats intubated with GLA conjugate showed the highest bloo d glucose levels and accelerated cataract development. The conjugate treatm ent also decreased lenticular GSH content. Conclusions The hypoglycemic effects of LPA are beneficial in the preventio n of acute symptoms of Type 2 diabetes. It remains to be shown that the ant ioxidant activity of LPA is responsible For prevention or inhibition of cat aract progression in sand rats. Copyright (C) 2000 John Wiley & Sons, Ltd.