Abstract
Objective 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. Patients and Methods. The study sample consisted of 120 patients diagnosed with primary or recurrent pterygium. Five groups of tissue samples were examined: control, primary pterygium, recurrent pterygium, and two groups of primary pterygium given a one-month NAC presurgery treatment (topical or systemic). The levels of endothelial nitric oxide synthase (eNOS), nitric oxide (NO), 3-nitrotyrosine (3NT), reduced and oxidized glutathione (GSH and GSSG), and catalase (CAT) were evaluated in tissue homogenates. Results Compared with 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 reduced in the other pterygium groups. GSH and CAT were enhanced in recurrent pterygium and systemic-treated primary pterygium 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. Women showed a higher level of GSH and catalase in primary pterygium, whereas a lower level of GSH and a higher level of NO in recurrent pterygium. Conclusion 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 reduced S-nitrosylation of GSH or other thiols and possibly to the modulation of the intracellular level of GSH through synthesis and/or mobilization from other tissues.
Highlights
Pterygium is triggered by a degenerative lesion in the conjunctiva and cornea of the eye and proceeds to fibrous tissue growth on the surface of the cornea
Taking into account all patients with primary pterygium who used the service of the hospital, the percentage of recurrence was 17% for all patients, 19% for men, and 16% for women
For the maintenance of redox homeostasis in the eye, GSH plays an essential role in cells and tissues as well as the tear film
Summary
Pterygium is triggered by a degenerative lesion in the conjunctiva and cornea of the eye and proceeds to fibrous tissue growth on the surface of the cornea. This condition can cause damage to DNA, other critical biological molecules, and the structure of the cell membrane. This type of cell damage can contribute to the pathogenesis of different ocular diseases. These molecules are important for cell signaling, involved in mechanisms for modulating and adapting to oxidative stress in a multitude of tissues. E overall effect of NO and related molecules revolves around the balance between the positive physiological ramifications of their signaling and the negative consequences of oxidative stress Reports on NO in Journal of Ophthalmology pterygium tissue are contradictory, as both low [6] and high levels [7] have been found, the latter reflecting probably the quantity of women in the study (by the higher levels of NO in women, compared with men). e overall effect of NO and related molecules revolves around the balance between the positive physiological ramifications of their signaling and the negative consequences of oxidative stress
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