Preventive effect of topical vitamin E-containing liposome instillation on the progression of galactose cataract. Comparison between 5-week- and 12-week-old rats fed a 25% galactose diet.

The preventive effect of topical vitamin E-containing liposome instillation on the progression of galactose cataract was compared between 5-week- and 12-week-old Wistar rats fed a 25% galactose diet. Vitamin E-containing liposomes [LP(+VE)] and vitamin E-free liposomes [LP(-VE)] were prepared with dipalmitoylphosphatidylcholine and dioleoylphosphatidylcholine (7:3 w/w). Twice daily instillation of either LP(-VE) or LP(-VE) into both eyes of 5-week-old rats fed the galactose diet for 18 days (5WGR) and 12-week-old rats fed the galactose diet for 7 weeks (12WGR) at which time some vacuoles appeared in the lens cortical equator, was conducted for a period of 4 and 9 weeks, respectively. The severity of cataracts at the end of instillation was similar in 5WGR and 12WGR. Instillation of LP(+VE), but not LP(-VE), retarded cataract progression in 5WGR and 12WGR. In 12WGR, LP(-VE) instillation caused a transient retardation of the progression. In lenses of 5WGR and 12WGR, decreases in vitamin E and reduced glutathione contents and increases in lipid peroxide, galactitol, and water contents occurred at the onset of instillation. For 5WGR, a decrease in lens reduced glutathione content and increases in lens vitamin E, lipid peroxide, galactitol, and water contents occurred at the end of instillation. For 12WGR, decreases in lens reduced glutathione and vitamin E contents and increases in lens lipid peroxide, galactitol, and water contents occurred at the end of instillation. In sera of 5WGR and 12WGR, vitamin E concentration decreased at the onset of instillation increased at the end in 5WGR and was unchanged in 12WGR. In 5WGR, instillation of LP(+VE), but not LP(-VE), for 4 weeks prevented these changes except the changes in lens galactitol and water contents and serum vitamin E concentration. In 12WGR, instillation of LP(+VE), but not LP(-VE), for 9 weeks prevented these changes except the changes in lens galactitol and water contents and serum vitamin E concentration. These results indicate that topically instilled LP(+VE) can retard cataract progression in 5WGR and 12WGR, mainly by the antioxidative action of vitamin E contained in the instilled liposomes.