Investigation of protective effect of carvacrol against paclitaxel-induced ototoxicity on rat model

Purpose: Ototoxicity is an important cause of hearing loss and balance system disorders. The aim of our study is to investigate the protective effect of carvacrol, a neuroprotective and antioxidant agent, on paclitaxel induced ototoxicity in rat model by using histopathological and biochemical methods and distortion product otoacoustic emissions. Materials and Methods: Experimental animals were divided into 5 groups as 8 rats in each group. At the beginning of the study, otoscopic examination and distortion product autoacoustic emission (DPOAE) measurements were performed on all rats. Rats with normal external auditory canal, tympanic membrane and hearing level were included in the study. No application was made to rats in group 1 until the end of study. 25 mg / kg Carvacrol was administered intraperitoneally to rats in group 2 once a week for 4 weeks. 5 mg / kg Paclitaxel was administered intraperitoneally to rats in group 3 once a week for 4 weeks. 5 mg / kg Paclitaxel and after 30 minutes 25 mg / kg Carvacrol adminestered intraperitoneally once a week for 4 weeks to rats in group 4. 25 mg / kg Carvacrol and after 1 day 5 mg / kg Paclitaxel adminestered intraperitoneally once a week for 4 weeks to rats in group 5. After 4 weeks, DPOAE measurements were repeated under general anesthesia. The temporal bones of rats sacrificed by the application of lethal dose of ketamine were removed. Histopathologic and biochemical examinations were performed. Results: There was no statistically significant difference in histopathologic examination, DPOAE measurements and antioxidant parameters in group 1, 2, 4, and 5. In group 3, histopathological sections showed significant damage, DPOAE measurements showed statistically significant decrease at 6000 and 8000 Hz, antioxidant activity decreased and markers of oxidative damage increased. Conclusion: We demonstrated that systemic carvacrol treatment has a potential protective role on paclitaxel-induced ototoxicity when assessed by DPOAE, histopathological methods and antioxidant parameters and may protect the cochlear morphology and functions due to antioxidant and neuroprotective properties. Keywords: Carvacrol, ototoxicity, paclitaxel.