Background: The early onset of cataract during diabetes may come about via a variety of pathogenic pathways, but an uncertainty about the significance of each of them exists.
Methods: Calf lenses cultured in a high glucose medium were investigated for regional variations in sorbitol accumulation, changes in lactate dehydrogenase activity, and formation of carbonyl groups in proteins. The results obtained were used to evaluate the contributions of various pathways to the alterations in the lens during hyperglycemia and to relate these findings to morphologically diverse lens substructures.
Results: The highest sorbitol accumulation was found in both the anterior and posterior cortex of lenses incubated in hyperglycemic medium. Lactate dehydrogenase activity was strongly affected by high sugar concentration, but the alterations in the equatorial part of lenses were more moderate relative to other substructures. After incubation with glucose, the concentration of Amadori products did not increase significantly compared to non-incubated and incubated controls. Nuclear proteins exhibited the highest level of oxidation.
Conclusion: The process of sorbitol accumulation is more evident than glycation in the initial stage of hyperglycemia. Lens cortex is affected faster by elevated glucose, while the nucleus is more susceptible to prolonged effects of oxidation, glycation, and glycoxidation.