A mild progression type of naphthalene-induced cataract in brown-Norway rats.
Naphthalene-induced rat cataract is a useful experimental cataract--however, because of its short survival period, studies using this model have been for limited purposes. Based on the consideration that the short survival might be caused by systemic toxicity of an overdose of naphthalene administration (1 g/kg body weight every other day), the authors successfully established a naphthalene-induced cataract with mild progression in Brown-Norway rats. The naphthalene administration proposed is to initially administer 0.5 g/kg and after a 1-week interval 1 g/kg of 10% naphthalene once or twice a week through a stomach tube. While the type of lens opacification induced in the two groups administered once and twice a week, respectively, was the same as that seen by the previous administration method, the progression of lens opacification seen in the groups showed a dose-dependent increase. The survival rate in the rats given naphthalene every other day according to the old method was 50% at the 6th week and 0% at the 9th week. Survival of the two new groups was 70 and 60% at the 30th week, respectively. This new type of naphthalene-induced rat cataract should be a suitable model for long-term observations.