Studies on cataractogenesis in humans and in rats with alloxan-induced diabetes. II. Histochemical evaluation of lenticular enzymes.

The effect of cataractogenesis on the behavior of some enzymes involved in glucose metabolism was examined histochemically both in human lenses and in rat lenses from rats with alloxan-induced diabetes. Several modifications in the currently available techniques were made in order to localize glucose-6-phosphate dehydrogenase, aldose reductase, sorbitol dehydrogenase, hexokinase and ketohexokinase in ocular lens. Human cataractous lenses showed a precipitous drop in glucose-6-phosphate dehydrogenase activity, whereas the lenticular tissues of alloxan-treated rats showed a gradual decrease of this enzyme with the prolongation of diabetes. Aldose reductase activity increased in hypermature and senile diabetic cataracts, whereas sorbitol dehydrogenase activity decreased in these lenses. Similarly, in alloxan-diabetic rat lenses the activity of aldose reductase increased while that of sorbitol dehydrogenase decreased with the prolongation of diabetes. Attempts were made to localize hexokinase and ketohexokinase in ocular lens.