The decomposition and aggregation of rat lens protein induced by selenite in vitro and in vivo.

A single subcutaneous injection of sodium selenite at the dose of 20 mumol/kg body weight induced bilateral nuclear cataracts in suckling rats. This selenite-induced cataract incidence can be increased by pretreating animals with a glutathione synthesis inhibitor. Sodium dodecyl sulfate polyacrylamide electrophoresis of urea-soluble proteins from selenite-induced cataractous lenses showed the appearance of high molecular weight aggregates and decomposed products of lens proteins. These products were found in association with the emergence of a 45 K band. Incubation of water-soluble lens proteins with selenite in vitro produced changes similar to those demonstrated in selenite-induced cataractous lenses. Furthermore, selenite induced the gradual development of opalescence and the oxidation of sulfhydryl in the lens protein solution. Therefore, we presume that the oxidation of lens protein sulfhydryl by selenite is associated with both aggregate formation and the decomposition of lens proteins, and that these changes may provide a partial explanation for the mechanism of selenite cataract.