Beneficial effect of lysine and amino acids on cataractogenesis in experimental diabetes through possible antiglycation of lens proteins.

Rats were given a single injection of streptozotocin. They became diabetic with a blood sugar of around 300 mg dL-1. They were divided into three groups of six rats each. Group II was the diabetic control. Each one of group III diabetic rats received daily 2 ml of 2% solution of lysine supplement orally. Group IV received daily 2 ml of a 2% solution of a mixture of amino acids supplement for 120 days. In addition there were 6 rats as normal control (Group I). Periodically ophthalmic examination was done by slit lamp. Blood glucose, proteins, hemoglobin, free amino acids, glycosylated hemoglobin and glycated lens proteins were also analysed. Body weight was recorded. The diabetic controls decreased in body weight. The blood sugar levels were lowered from about 295 mg dL-1 to 99 mg dL-1 in the lysine-fed group and from 268 mg dL-1 to 126 mg dL-1 in the amino acids mixture-fed group. The levels of glycosylated hemoglobin and glycated lens proteins increased in diabetic controls while they were normal in other groups. The free amino acid levels in blood were lower in groups receiving lysine or amino acids than in diabetic controls indicating their better utilization. In diabetic control, all the animals developed cataract in 70-90 days; five out of six did not develop cataract in the lysine supplemented group. Four of six did not develop cataract in the amino acid mixture-supplemented group. None developed cataract in normal controls. Lysine and amino acids have anticataractous and antidiabetic effects. Copyright 1998 Academic Press.