Carvacrol Protects Against Paclitaxel-Induced Retinal and Optic Nerve Cytotoxicity: A Histopathological Study

Objectives: Carvacrol (CV) is a phenolic monoterpenoid found in the essential oil of a number of aromatic plants and herbs. The present study was an investigation of the potential protective effect of CV against paclitaxel (PTX)-induced retinal and optic nerve cytotoxicity in rats.Methods: A total of 18 adult male Wistar albino rats (250-400g) were randomized into 3 equal groups comprising 6 ani-mals each. Group 1 (control group) received intraperitoneal (IP) saline solution (0.5 mL/200 g) weekly for 4 weeks. Group 2 received an IP dose of PTX (5 mg/kg), and Group 3 received CV (25 mg/kg) 30 minutes after an IP dose of PTX (5 mg/kg) weekly for 4 weeks. At the conclusion of the experimental period, the retinal and optic nerve tissues of the subjects were evaluated histopathologically.Results: All of the retinal specimens in Group 1 (control) were histopathologically normal. In Group 2 (PTX), all of the eyes (6/6) revealed increased retinal vascularity and rosette-like structures in the outer nuclear layer, and in Group 3 (PTX-CV), all of the eyes (6/6) demonstrated normal retinal vascularity and the absence of rosette-like structures. All of the optic nerve specimens in Group 1 (control) were histopathologically normal. In Group 2 (PTX), all of the eyes (6/6) demonstrated severe vacuolization and a decreased number of astrocytes and oligodendrocytes in the optic nerve specimens, while 3 eyes (3/6) showed marked single cell necrosis. None of the eyes in Group 3 (PTX-CV) demonstrated either vacuolization or a reduction in the number of astrocytes and oligodendrocytes. No remarkable single cell necrosis was observed in the optic nerve specimens of Group 3 (PTX-CV).Conclusion: The histopathological findings indicated that CV played a protective role against PTX-induced cytotoxicity. CV might be a promising resource to counteract oxidative stress-based cytotoxicity in the field of retinal and optic nerve disorders.