KBB-Forum 2017 , Cilt 16, Sayı 2

THE PROTECTIVE EFFECT OF THYMOL AGAINST CISPLATIN-INDUCED OTOTOXICITY: AN EXPERIMENTAL ANIMAL STUDY

İlker KOÇAK1, MD; Ömer Faruk ÜNAL1, MD; Esra AYDOĞAN1, MD; Remzi DOĞAN2, MD; Dilek AKAKIN3, MD; Kutay KÖROĞLU3, MD; Ömer Faruk ÖZER4 MD
1Koç Üniversitesi Hastanesi, Kulak Burun Boğaz , İstanbul, Turkey
2Bezmialem Vakıf Üniversitesi, Kulak Burun Boğaz , İstanbul, Turkey
3Marmara Üniversitesi, Histoloji ve Embriyoloji, İstanbul, Turkey
4Bezmialem Vakıf Üniversitesi, Biyokimya, İstanbul, Turkey Objective: The aim of this study is to investigate the protective effect of thymol against cisplatin- induced ototoxicity by evaluating audiological, biochemical and histopathological parameters.

Materials and methods: Thirty-two male rats were divided into four groups (control, cisplatin, thymol + cisplatin and thymol) including eight rats each. 150 mg/kg/day thymol was given for 5 days orally. Single dose cisplatin(16 mg/kg) was also given via intraperitoneal route. Distortion product otoacoustic emission(DPOAE) and auditory brainstem response(ABR) tests from both ears were performed in all groups at the beginning of the study and also on days 6. Intracardiac blood samples and their cochleas were taken on day 6 for assessment of biochemical and histopathological(including TUNEL) parameters.

Results: In audiological assessment, in group 2(cisplatin), there were significant decreases in DPOAE values and significant increases in ABR thresholds on days 6 as compared with other groups. In Groups 1(control), 3(thymol + cisplatin) and 4(thymol) there was no significant difference between the pre- and posttreatment DPOAE and ABR results.

In biochemichal analyses, the total oxidant status(TOS) value was significantly higher in group 2(cisplatin) than in the other groups. The total antioxidant status(TAS) value was significantly higher in group 3(thymol+cisplatin) than in group 2.

In the histopathological examinations, there was significant reduction of the number of TUNEL-positive cells in the group 3(thymol+cisplatin) compared to the group 2(cisplatin).

Conclusions: The audiologic tests, biochemical results and histologic findings revealed that thymol may have protective effect against cisplatin ototoxicity by increase antioxidant levels and reduce oxidative stress parameters. Keywords : Cisplatin, Thymol, Ototoxicity