Protective Role Of Glutathione And Role Of Nitric Oxide Production In The Pathogenesis Of Pterygium
Abstract Background: In the pathogenesis of pterygium, the protective role of glutathione and nitric oxide production is unclear. These are important factors for homeostasis in the redox state of cells. The aim of this study was to determine the levels of these and related parameters in pterygium tissue. Methods: Five groups of tissue samples were examined: control, primary pterygium, recurrent pterygium and two groups of primary pterygium given a one-month NAC pre-surgery treatment (topical or systemic). The levels of endothelial nitric oxide synthase (e-NOS), nitric oxide (NO), 3-nitrotyrosine (3NT), reduced and oxidized glutathione (GSH and GSSG), and catalase (CAT) were evaluated in tissue homogenates. Results: Compared to the control, decreased levels of eNOS, NO and 3-nitrotyrosine as well as the degree of oxidation of GSH (GSSG%) were observed in primary and recurrent pterygium. 3-Nitrotyrosine and GSSG% were also reduced in the other pterygium groups. GSH and CAT were enhanced in recurrent pterygium and systemic-treated, but were unchanged for topical-treated primary pterygium. There was a strong positive correlation of eNOS with NO and 3NT, GSSG% with NO and 3NT, and GSH with GSSG and CAT. Conclusions: The results are congruent with the following proposed sequence of events leading to a protective response of the organism during the pathogenesis of primary pterygium: a decreased level of eNOS provokes a decline in the level of NO in pterygium tissue, which then leads to the modulation of the intracellular level of GSH through synthesis and/or mobilization from other tissues.