N-甲-N-亚硝脲对大鼠视网膜光感受器的毒性作用

目的观察N-甲基-N-亚硝脲(N-methyl-N-nitrosourea,MNU)对SD大鼠视网膜光感受器细胞的毒性作用.方法雌性SD大鼠100只,分17组,正常对照组4只,其余组各6只.在大鼠生后50 d,分别一次腹腔注射MNU 50mg/kg、60mg/kg、70mg/kg和80mg/kg.在MNU处理后24、48、72 h和7 d处死大鼠,取眼球,做组织学检查.结果不同剂量的MNU均引起中心视网膜和周边视网膜损伤,其损害的程度与MNU的剂量呈正比.作用24 h后,可见视网膜光感受器细胞核固缩、破坏及光感受器外节部定向紊乱;48 h或72 h后,可见光感受器细胞丧失;7 d后,外颗粒层和光感受层几乎完全消失.结论MNU对大鼠视网膜光感受器细胞有选择性的毒性作用,该作用呈剂量和时间依赖性.

The Toxic Effect of N-methyl-N- nitrosourea on Retina in Rats

PURPOSE: To observe the toxic effect of N-methyl-N-nitrosourea (MNU) on photoreceptor cells within retina of SD rats. METHODS: At 50 days of age, 100 female rats received a single intraperitoneal injection of MNU at different doses of 50 mg/kg, 60 mg/kg, 70 mg/kg and 80 mg/kg body weight, respectively. Each group had 6 rats and 4 untreated rats were used as normal control. At 24, 48 and 72 hours and 7 days after the administration of MNU, the animals were sacrificed and both eyes were enucleated immediately and processed for histological examination. RESULTS: It was found that all doses of MNU could sequentially damage the central and peripheral retina. The first evidence of retinapathy 24 hours after the application of MNU was pyknosis and disruption of photoreceptor cells nuclei and the disorientation of the photoreceptor outer segments; loss of photoreceptor cell deteriorated significantly at 48 hours or 72 hours; the outer nuclear layer and photoreceptor layer were almost completely lost at 7 days. CONCLUSION: The results demonstrated that MNU could selectively damage the photoreceptor cells in the retina of the rats, which was dose-dependent and time-dependent.