protective effects of vitamin E versus vitamin C against cisplatin ototoxicity in guinea pigs [histological and audiological study]

The protective effects of both vitamin E and C against cisplatin induced ototoxicity were assessed histologically and audiogically. This was done by quantifying the extent of cochlear damage with the light microscope, scanning electron microscope and with measurement of the Distortion Product Otoacoustic Emissions [DPOAEs]. Twenty-five adult male guinea pigs were used in this study. They were divided into control group, cisplatin group that was injected 8 mg/kg cisplatin intra-peritoneally [i.p.], vitamin E group that was injected 500 mg/kg of vitamin E i.p.30 mm prior to cisplatin injection, and vitamin C group which was given 200 mg/kg of vitamin C i.p. 30 min before cisplatin administration. When administered alone, cisplatin induced loss and vacuolation of outer hair cells [OHCs] as seen by LM examination. Scanning EM revealed fusion, disarrangement and loss of some stereocilia in the remaining OHCs especially in the basal turn. In contrast, inner hair cells resisted cisplatin ototoxicity. Audiological assessment demonstrated reduction in DPOAEs amplitudes and S/N values in all frequencies. Both vitamin E and C reduced cisplatin ototoxicity, with better protection achieved by vitamin C administration. Scanning EM examination showed that OHCs were similar to the control configuration after vitamin C administration while after protection with vitamin E, OHCs of the third row showed fusion and absorption of the stereocilia in some parts. In addition, both DPOAEs amplitudes and S/N ratio were near the control values up to 4 KHz. However, above 4 KHz both vitamins failed to achieve the full protection, with vitamin C showing better performance in these high frequencies. We conclude that both vitamins had protective effects against cisplatin induced ototoxicity, with vitamin C inducing more protection in the used regimen