Round Window Membrane Application Of N-L-acetylcysteine And/or Caroverine Can Protect The Cochlea Against Neomycin Ototoxicity

Objective: The aim of this study was to text whether antioxidant N-L-acetylcysteine and/or glutamate receptor antagonist caroverine can successfully protect the cochlea from neomycin-induced ototoxicity using round window membrane local application. Whether the effect of local combinated application was better than NAC or Car alone. Method: 40 healthy guinea pig was devided randomly into 4 groups and each group had 10 animals. Before round window membrane administration auditory brainstem responds(ABR) threshold of all animals must were measured and undergo surgery to exposure the right round window niche. Then, the drugs were dropped onto gelfoam and the gelfoam was placed onto the round window niche.4 groups were administrated: normal saline (1ml/kg) , N-L-acetylcysteine (1ml/kg) , caroverine (12.8mg/ml, 60ul/kg) and N-L-acetylcysteine (1ml/kg) plus caroverine (12.8mg/ml, 60ul/kg) respectivly and 50% neomycin was dropped into gelfoam after 30 minutes. ABR measurements were performed again after 14d.Then, the animals were killed and right bullar were obtained. The cochlea were fixed by 4% paraformaldehyde . Phalloidin staining were used. Hair cell counting were counted using fluorescence microscope. Result: Comparing experment group with the control group, the average threshold of the N-L-acetylcysteine (NAC) group, the caroverine(Car) group and the NAC+Car group were ameliorated 27dB,28dB and 37dB respectively, the difference was significant (P<0. 01) between the control and all tested groups, the difference was significant ( P<0. 01) between the NAC/Car group and the NAC+Car group. The mean...