Rapid induction of cataract by a single intraperitoneal administration of N-methyl-N-nitrosourea in 15-day-old Sprague-Dawley (Jcl: SD) rats.

Cataract was induced by a single intraperitoneal injection of N-methyl-N-nitrosourea (MNU) in 15-day-old Sprague-Dawley (Jcl: SD) rats. The threshold dose of MNU required for cataract induction in a 3-4 week time period was 70 mg/kg; 60 mg/kg was ineffective. Males and females were both equally affected. Mature cataract as confirmed histologically by degeneration, swelling, vacuolation, liquefaction of the lens fibers, and formation of Morgagni-like water vacuoles was seen in 80% (8/10), 70% (7/10) and 90% (9/10) of 100, 80 and 70 mg/kg MNU-treated rats, respectively, 4 weeks after dosing (43 days of age). At this time point, lens epithelial apoptosis was only rarely seen, but proliferating cell nuclear antigen (PCNA) labeled atypical nuclei with vacuolated lens fibers and macrophage migration were present within the injured lens. Cataracts were the only lesions induced by MNU and there were no other intra- or extraocular lesions seen. The dosing and timing schedule for the MNU administration in rats used in the present study is effective in rapidly causing cataract to occur.