Investigation of the effects of quercetin in the treatment of experimental corneal alkali burns in rats

ABSTRACT Ekin M, Investigation of the Effects of Quercetin in the Treatment of Experimental Corneal Alkali Burns in Rats, Van Yüzüncü Yıl University, Institute of Health Sciences, Department of Veterinary Surgery, Ph.D. Thesis, Van, 2025.The aim of the study was to investigate the clinical, biochemical, histopathological and immunohistochemical efficacy of different doses of quercetin in the form of drops on corneal healing in the treatment of experimentally induced corneal alkaline burns with sodium hydroxide in rats. For this purpose, a total of 64 Wister albino male rats were used in the study. After local anesthesia was applied to the right eyes of the rats under general anesthesia, where alkaline burns would be induced, an alkaline burn model was created in the center of the cornea with 3 mm diameter Whatman filter paper impregnated with 25 µl 1 N NaOH. The rats with alkaline burns in their right corneas were randomly divided into 4 main groups, each with 16 rats. The animals in these main groups were randomly divided into 2 subgroups, each with 8 animals, to be sacrificed on the 7th and 14th days. Drops containing 5% DMSO, which was used as the vehicle in which quercetin was dissolved, 0.1% quercetin in group D, 0.5% quercetin in group O, and 1% quercetin in group Y were instilled into the eyes of rats, one drop at a time, three times a day throughout the study. For clinical evaluation, photographs were taken on the 0th, 3rd, 7th, and 14th days after alkaline burn was created in the cornea, and corneal neovascularization and epithelial defect area were measured. At the end of the 7th and 14th days, VEGF and TGF-β levels were biochemically evaluated in the corneas of the rabbits that were sacrificed, histopathologically evaluated in terms of neovascularization, epithelial, and collagen loss, and immunohistochemically evaluated in terms of caspase-3, TNF-α, and IL-6 expressions. Clinically, neovascularization score was found to be significantly lower in group D compared to the control group on the 7th day (p<0.05). In epithelial regeneration measurements, corneal reepithelialization was found to be statistically significantly higher in groups D and O compared to the control group on the 7th and 14th days (p<0.05). VEGF level was found to be significantly lower in group D compared to the control group only on the 7th and 14th days, while TGF-β level was observed to be significantly lower in groups Y and O compared to the control group only on the 14th day (p<0.05). Histopathological and immunohistochemical findings revealed that groups D and O showed better results in corneal healing compared to the control group. As a result, it was concluded that quercetin at low doses contributes to corneal healing in the treatment of corneal alkali burns by suppressing neovascularization, collagen fiber loss, inflammation by suppressing TNF-α and IL-6 expression, reducing apoptosis by suppressing caspase-3 expression, and increasing corneal epithelialization; however, in order to more clearly demonstrate its efficacy and reliability, advanced comprehensive studies are needed in different solvents, at different dosages, especially at doses between 0.5-0.1% and at lower doses. Keywords: Eye, Corneal Alkali Burn, Quercetin, Rat.