A Model of NIHL guinea pig for study of cochlear hair cell regeneration in mammalian

Objective To study the change of the guinea pig cochlea after high-intensity impulse noise exposure in order to assess its effects on hearing,and to discuss the methods of the noise deafness animal model for cochlea hair cell regeneration research.Methods Fifty adult guinea pigs were used,weight between 250 and 300g,and were divided into two groups in random.Fourty animals were incessant exposed to impulse noise 200 times(Pressure peak was 175.0 dB SPL,and Pulse duration was 0.25 ms,interval time 20s).For exposed group,10 were used as control group.Cochlear hair cell counting,Immunohistochemical-dyeing cochlea stretched preparation,and Audtory brainstem response(ABR) thresholds were determined before and 1 week,4 weeks and 8 weeks after exposed.Results One week after exposed to high-intensity impulse noise,there were 21 of the 40 guinea pigs(52.5%),with ABR thresholds ≥ 95 dB SPL at every frequency,but not recovered after 8 weeks.No significant change of the ABR thresholds between 1 week,4 weeks and 8 weeks(P 0.05).Cochlea hair cell counting showed the average miss rate of inner hair cell is 91.4%;the outer hair cellis 97.2% in 1week after noise exposure.Immunohistochemical results showed,that most of the nucleus of the inner hair cell and outer hair cell were missed,but the supporting cell nucleus of the inner hair cell medial and outer hair cell lateral still existed in one week after noise exposure.Conclusion High-intensity impulse noise exposure may cause severe sensorineural deafness,and cochlear hair cells were generally missed and can not recover automatically,but most of the supporting cells were existed.This noise deafness animal model is promise of an ideal animal model for the further study for acoustic hair cell regeneration.