Damage of photoreceptor cells by N-methyl-N-nitrosourea in cats / 中华实验眼科杂志

ABSTRACT

Background To establish the ideal animal model of retinitis pigmentosa (RP) is very important for onward relevant study.Previous research determined that N-methyl-N-nitrosourea (MNU) can selectively damage photoreceptors via intravenous injection in mammal.However,whether MNU can be used to create an RP model needs to be investigated.Objective This experiment was designed to evaluate the toxic effect of MNU on photoreceptor cells of cats.Methods MNU was injected into 20 2-year-old cats via femoral vein and randomized into 20mg/kg, 25mg/kg, 30mg/kg, 35mg/kg and 40mg/kg MNU groups,and equal amount of normal saline solution was used in the same way in 4 normal cats as the control group.The activity,pupil size and light reflex were observed after injection of MNU.The cats were sacrificed and eyeballs were enucleated for histological examination to evaluate the structural and morphological changes of photoreceptors at 24 hours,72 hours,7 days and 14 days after the administration of MNU.This experimental study complied with the Statement for the Use of Animals in Ophthalmic and Vision Research.Results Dilated pupil and inertia of light reaction were found in experimental cats on the 7th days in the various groups.In 24 hours after MNU injection,the damage of photoreceptors was primarily characterized by pyknosis and disorder.In 72 hours after MNU injection,attenuation of the outer nuclear layer and disruption of cells were seen.Loss of photoreceptors and disappearance of the outer nuclear layer were observed on the 7th and 14th day.The extent of retinal photoreceptor cell damage was dependent on the dose of MNU.Conclusion MNU can selectively induce serious damage of the photoreceptor cells in cats retina in a time- and dose-dependent manner.