Ototoxicity in Guinea Pigs: NO Levels in Cochlear Fluids

Abstract

Problem Ototoxicity continues to be the most common side effect of gentamicin, and its physiopathology is still unclear. Currently the main accepted theory relates the ototoxicity with over production of free radicals, like nitric oxide (NO). Objective: To analyze the NO levels in the cochlear fluids of guinea pigs exposes to gentamicin and its relation with ototoxicity and propose an experimental model to study ototoxicity and drugs that may prevent it. Methods Six guinea pigs were used, divided in two groups: a) Study – submitted to intraperitoneal injections of gentamicin, (135mg/kg/day) for 14days; b) Control - submitted to intraperitoneal injections of distilled water, daily, for 14days; the hearing loss was evaluated with Preyer's reflex. On 14 day the guinea pigs were sacrificed and the cochlear fluids were collected for dosage of the nitric oxide through the chemiluminescence method (NOA-TM 280). Results The Preyer's reflex was absent at the end of the experiment in the Study group, what did not happen in the control group. The average of the nitric oxide levels of the guinea pigs of the study group was 26.2μ and the Control group 11.26μM. Conclusion It was possible to measure nitric oxide levels in guinea pigs cochlear fluids. The results reinforce the role of nitric oxide in ototoxicity induced by gentamicin. Significance Experimental study (Level 2).