Preventive and therapeutical effects of N-acetylcysteine on selenite-induced cataract in vivo / 中华实验眼科杂志

ABSTRACT

Background The mechanism of both selenite-induced cataract and age-related cataract is oxidative damage.N-acetylcysteine (NAC) is one of the effective antioxidants,but the literature is little about the preventive and treating effects of NAC on cataract. Objective This study attempted to investigate the preventive and therapeutical effects of NAC on the selenite-induced cataract,and to discuss the possible mechanism. Methods Sixty 10-day-old clean SD rats were randomly divided into normal control group-1,normal control group-2,selenite-induced cataract group,NAC preventive group,NAC+normal saline group and NAC treatment group.Selenite cataract models were induced by subcutaneous injection of 3.46 mg/kg sodium selenite once daily for three days.The rats of NAC preventive group received the intraperitoneal injection of 2 mmol/L NAC 30 minutes before the injection of sodium selenite once daily for 6 days.In NAC treating group,2 mmol/L NAC was intraperitoneally injected 1 day after the injection of sodium selenite for 30 days,and the normal saline solution was injected at the same method in the NAC+normal saline group.Lens opacification was graded according to LOCS Ⅲ criteria.Histopathological change of lens epithelium was examined under a light microscope after hemotoxylin and eosin staining,and the ultrastructure was observed under the scanning electron microscope.The expression of caspase-3 in lens was assayed using immunochemistry.The levels of superoxide dismutase ( SOD ),malonaldehyde ( MDA ) in rat lens were detected respectively in corresponding time points.The use of the experimental animals complied with the Regulation for the Administration of Affairs Concerning Experimental Animals by State Science and Technology Committee. Results In 7 days after experiment,lenses were completely clear in the normal control group.Lens opacification of Ⅴ grade was found in 11 eyes in selenite cataract model group,but no lens opacification of Ⅴ grade was seen in NAC preventive group,showing a significant difference(x2 =40.000,P＜0.05 ).In 30 days after experiment,Ⅳ- Ⅴ grades of cataracts were found in 20 eyes both in NAC + normal saline group and NAC treating group (x2=0.153,P＞ 0.05 ).Histopathological examination showed that lens structure was normal,and the separation between LECs and anterior capsule,the rupture of cellular membrane,deformation of cellular nuclei and the feature of lens fiber were seen in selenite cataract group,but the damage of lens was mild in the NAC preventive group.Ultrastructure of lens was obviously abnormal in selenite cataract group,NAC+normal saline group and NAC treating group.Expressions of caspase-3 and SOD in lens were significantly lower,but that of MDA was significantly higher in the selenite cataract group than the normal control group (P＜0.05) ;while those of the NAC preventive group were significantly different from selenite cataract group(P＜0.05).No significant difference was found in the expressions of caspase-3 and the levels of SOD and MDA between NAC+normal saline group and NAC treating group (P＞0.05 ). Conclusions Selenite can induce the apoptosis of LECs.NAC can evidently postpone formation of selenite cataract by increasing the activity of SOD,decreasing the level of MDA and the expression of caspase-3.However,NAC could not reverse selenite-induced lens damage.