Pterygium: Glutathione, Nitric Oxide Production and N-Acetylcysteine Treatment

Abstract Background There was not investigated the participation of glutathione (GSH), endothelial nitric oxide synthase (eNOS) and nitric oxide (NO) in pterygium pathogenesis and the effects of the precursor of GSH synthesis N-acetylcysteine in treatment prior to surgery.Methods The levels of eNOS, NO, 3-nitrotyrosine, reduced and oxidized GSH (GSSG) and catalase were measured in tissue homogenates of 120 patients with primary or recurrent pterygium, and systemic or topical pretreatment with N-acetylcysteine, compared to control group.Results A decrease in eNOS, NO, 3-nitrotyrosine, and GSH oxidation degree (GSSG%) was observed in primary pterygium, which remained decreased in other pathological groups in case of GSSG% and 3-nitrotyrosine. The levels of GSH and catalase increased in recurrent pterygium, even more, they increased in the group with systemic treatment, while topical treatment did not affect them, compared with control or primary pterygium groups. High positive correlation in groups of the study was observed between behavior of eNOS with NO or GSSG%, while GSH showed it with GSSG or catalase. Women showed a higher level of GSH and catalase in primary pterygium group, lower its level and a higher level of NO in recurrent pterygium. It was observed in women positive correlation in groups of study of GSSG% with 3-nitrotyrosine alone, while in men with NO.Conclusions Study data do not contradict the assumption about the following possible sequence of events in pathogenesis of the primary pterygium: decrease in the activity of eNOS and consequently of NO, decrease in S-nitrosation of GSH, possible modulation of the intracellular level of GSH through synthesis and/or mobilization from other tissues.