¡¡¡¡DISCUSSION

¡¡¡¡The current results presented here provided evidence to support that NAC and Tau can protect the damages induced by hyperoxia. It¬ðs well known that the GSH system plays a key role in the protection against oxidative stress, which is quantitatively the most important endogenous rechargeable antioxidant and functions as an essential antioxidant vital for maintenance of the tissue¬ðs transparency [9]. Decreased GSH is found in many cataractous lenses.

¡¡¡¡NAC, a precursor of glutathione, has been used effectively to replenish intracellular glutathione stores directly and conª²veniently. It is an excellent source of sulfhydryl (ª²SH) groups, and is converted in the body into metabolites capable of stimulating GSH synthesis. Tau is an important nonª²enzymatic system antioxidant in the lens. It plays a critical role in maintaining the normal metabolism of lens and maintaining its transparence [7]. The mechanism of its antiª²oxidative effect is to protect lens from oxidative injury mainly by resisting lipid peroxidative reaction. Further research shows that Tau may react with hypochlorous acid or hypochlorous acid metal compound to eliminate the redundant hydroxyl free radical, and inhibit cell edema by adjusting osmotic pressure at the same time[10]. NAC and Tau have different effects on lens damages induced by hyperoxia. Therefore, the GSH content and all enzymes activities were distinguishable.

¡¡¡¡Our present study has demonstrated that oxidative injury induced by hyperoxia could lead to the opacification of lens. All measured parameters showed the effect of the NAC was superior to Tau. And these results are the first report on a possible role for NAC in the prevention of the hyperoxiaª²induced damages in rabbit lens. It appears that the protective effects of NAC against oxidative lenticular damage are evidently, through its favorable effect on GSH, catalase and Na, Kª²ATPase activities. In conclusion, these results of the present investigation suggest that NAC is superior than Tau to significantly retard experimental hyperoxiaª²induced lens damages and provides futher evidence for the research of NAC.

¡¾²Î¿¼ÎÄÏס¿
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