Local and systemic antioxidant status in experimental purulent corneal ulcer

Aim. To examine the systemic and local (corneal) free radical status in rabbits with experimental purulent corneal ulcers. Methods. The study was performed on the male chinchilla rabbits with an average weight of 3500±200 g 10 intact rabbits (10 eyes) served as controls. Staphylococcal purulent corneal ulcer was modeled on 40 animals (40 eyes) as described by N.A. Adamova (1999). The animals were euthanized at 3rd, 7th, 14th, and 21st day of the experiment. The concentration of malondialdehyde, protein-free thiols, as well as superoxide dismutase, glutathione peroxidase and glutathione-S-transferase activity were determined in cornea homogenate and erythrocyte lysate. The obtained data were processed by the one-factorial dispersive analysis (ANOVA), Newman-Keuls test. Results. In all animals the purulent ulcer occurred 12-24 hours after staphylococcus culture introduction. From day 1 to day 3 of the experiment, the clinical picture of a purulent ulcer corresponded to an infiltration stage. From day 3 to day 7 of the experiment, palpebral edema developed, the purulent discharge lasted out, and in some cases even intensified. From day 7 to day 21 of the experiment, corneal infiltration decreased both by area and intensity. In 11,1% scaring corneal opacity formation began. Experimental purulent corneal ulcer development was accompanied by lipid peroxidation activation both in cornea and in erythrocytes, shown by increased malondialdehyde concentration, decreased protein-free thiols level and antioxidant glutathione peroxidase, glutathione-S-transferase and superoxide dismutase enzymes activity. There was a strong direct relationship between the erythrocyte malondialdehyde level and corneal malondialdehyde concentration, and inverse relationship between erythrocyte malondialdehyde level and erythrocyte superoxide dismutase activity. Conclusion. The development of experimental staphylococcal corneal ulcers is accompanied by the development of local and systemic oxidative stress.

experimental corneal ulcer, oxidative stress, cornea, erythrocytes, lipid peroxidation