Biochemical changes and cataract formation in lenses from rats receiving multiple, low doses of sodium selenite.

Nuclear cataract formed in rat lens in response to a protocol of multiple, low doses of sodium selenite. Nuclear cataract occurred, in both Wistar and Sprague-Dawley rats, following five subcutaneous injections of selenite over an 8-day period with an accumulated dose of 40-50 nmol selenite g-1 body weight. Glutathione content decreased within the first 24 hr of treatment and remained at 60% of controls. Lipid peroxidation occurred in Wistar rats prior to nuclear cataract formation. A two to three-fold increase in calcium concentration and decreased protein content accompanied nuclear cataract development. Enzyme activities were measured for glutathione peroxidase, glutathione reductase, and glutathione S-transferase, and only the peroxidase activity remained constant through the period of cataract formation. This protocol resulted in nuclear cataracts similar in appearance to those observed with a single, acute dose of selenite. The opportunity to control the rate of selenite-dependent cataract formation allows further definition of precataractous events.