Publication: Changes of superoxide dismutase, catalase and glutathione peroxidase in the corneal epithelium after UVB rays. Histochemical and biochemical study
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Date
2000
Authors
Cejkova, J. ; Stipek, S. ; Crkovska, J. ; Ardan, T.
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Publisher
Murcia : F. Hernández
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DOI
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info:eu-repo/semantics/article
Description
Abstract
In this study, the effects of UVA and UVB
rays on antioxidant enzymes (superoxide dismutase,
glutathione peroxidase, catalase) were examined in the
corneal epithelium. The corneas of albino rabbits were
irradiated with a UV lamp generating UVA (365 nm
wavelength) or UVB rays (312 nm wavelength), 1 X
daily for 5 min, from a distance of 0.03 m, over 4 days
(shorter procedure) or 8 days (longer procedure). In
contrast to UVA rays, which did not evoke significant
disturbances, UVB rays changed the activities of
antioxidant enzymes. The longer repeated irradiation
with UVB rays was performed, the deeper the observed
decrease in antioxidant enzymes. The shorter procedure
evoked a more profound decrease of glutathione
peroxidase and catalase (the enzymes cleaving hydrogen
peroxide) than of superoxide dismutase, an enzyme
scavenging superoxide radical and producing hydrogen
peroxide during the dismutation reaction of a superoxide
free radical. This may contribute to an insufficient
hydrogen peroxide cleavage at the corneal surface and
danger to the cornea from oxidative damage. After the
longer procedure (UVB rays), the activities of all
antioxidant enzymes were very low or completely
absent. In conclusion, repeated irradiation of the cornea
with UVB rays evokes a deficiency in antioxidant
enzymes in the corneal epithelium, which very probably
contributes to the damage of the cornea (and possibly
also deeper parts of the eye) from UVB rays and the
reactive oxygen products generated by them.
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