Relationship between Experimentally Induced-Steroid Cataract and Vitamin E

Abstract

This communication has described the relationship between steroid cataract and vitamin E (E) in an in vitro steroid cataract model based on the following results that we have obtained so far. When isolated rat lenses were incubated in TC-199 culture medium containing methylprednisolone (MP) (1.5 mg/ml) over a 72-h period, a faint opacity appeared in the equator at 12 h after culture initiation and whole cortical opacity occurred at 72 h. E level decreased at 72 h after culture initiation, while a decrease in reduced glutathione (GSH) level and an increase in lipid peroxide (LPO) level occurred at 48 h or later. The activity of glyceraldehyde-3-phosphate dehydrogenase ( GAP-DH ), an index of oxidative damage, decreased at 24 h after culture initiation or later. Na^+/K^+ ratio increased before opacity formation. This increase was enhanced as opacity progressed. An increase in water content and a decrease in Na^+, K^+-ATPase activity were seen at 48 h after culture initiation or later. Simultaneous treatment with E prevented MP-induced lens opacification. When lenses cultured with MP were treated with E at 24 and 48 h during the culture period of 72 h, the treatment at 24 h, but not at 48 h, was effective. E level in lenses treated with MP and E, irrespective of the timing of E treatment, increased with an increase in culture time and this increased E level was much higher than that in either lenses treated with MP alone or untreated lenses. When lenses with the same severity of MP-induced early cortical opacity were further cultured in medium containing MP and E for 48 h, opacity progression was prevented. The opaque lenses further cultured with MP alone showed a decrease in E level and an increase in water content in addition to further increases in LPO level and Na^+/K^+ ratio and further decreases in GSH level and GAP-DH and Na^+, K^+ -ATPase activities. The changes in these components and enzymes except GSH were attenuated in the opaque lenses further cultured with MP and E. These results indicate that MP-induced cataract is closely related to E in cultured rat lenses and that E can prevent the progression of this MP-induced cataract through its antioxidative and membrane-stabilizing actions. Thus, it canbe anticipated that E becomes an anti-cataract drug for steroid cataracts.