三硝基甲苯致白内障机理及其在晶状体内代谢的研究

在建立TNT大鼠白内障的基础上,用HPLC分析了晶状体内TNT及其代谢产物,并用ESR及NBT方法检测了TNT在晶状体内的代谢过程所产生的自由基。结果表明,慢性染毒24个月的大鼠白内障晶状体内含有TNT原形和4氨基2,6二硝基甲苯代谢产物,以及在体外与正常晶状体微粒体孵育可产生TNT硝基阴离子自由基和超氧阴离子自由基。上述结果提示,TNT可进入晶状体内,在其还原代谢过程中产生硝基阴离子自由基中间产物,在有氧条件下进而产生超氧阴离子自由基,这可能是TNT导致白内障的启动因素。

Studies on Mechanism of 2,4,6-Trinitrotoluene (TNT)Induced Cataract and TNT Metabolites in Rat Lens

Persons exposed to TNT over a considerably long period of time have a high incidence of cataract. Up to now, however, the metabolism and toxicological mechanism of TNT in lens remains to be clarified. An experimental animal model of TNT cataract has been established in our laboratory. In this study (1)HPLC was employed to analyse TNT and its metabolites in TNT induced cataractous lens of rat; (2) electron spin resonance spectra was used to identify the formation of TNT-nitro anion radicals; (3) and nitroblue tetrazolium (NBT) reduction method was applied to detect the generation of superoxide radicals in TNT/lens microsome/NADPH incubation system. The result showed: (1) The TNT and its metabolite 4-amino-2,6-dinitrotoluene was present in lens extract from rats received injection of TNT up to 24 months; (2) When TNT (0.2mmol/L) was incubated with rat lens microsomes (equivalent to 1mg/mL protein), NADPH generating system and riboflavin (0.01mmol/L) in oxygen free condition, the hyperfine pattern electron spin resonance spectra of TNT anion radicals were identified; (3) If the incubation mixture was not oxygen-free, the superoxide radicals were detected. Our results suggest that TNT molecules can pass through the barrier of blood-aqueous humour, penetrate into the lens and be reductively activated in lens epithelia cells to give the first intermediate of TNT-nitro anion radicals, which in the presence of oxygen rapidly donate an electron to oxygen to form superoxide radicals. We believe that these may be the initiating cause of TNT cataract formation.