多种强度噪声对C57BL/6J小鼠听力损失的观察研究OA

Objective:To establish the hearing loss model of C57BL/6J mice induced by various intensities of noise,and to observe the effects of different intensities of noise on C57BL/6J mice hearing and cochlear hair cells.Methods:A total of twenty-five C57BL/6J mice with normal hearing were randomly divided into 5 groups with 5 mice in each group.The groups were as follows:the blank control group was not exposed to noise,the 96 dB group,the 100 dB group,the 105 dB group,the 110 dB group,their noise exposure intensity was 96,100,105,110 dB SPL,the frequency was 8‒20 kHz,the exposure time was 2 hours.Auditory brainstem response(ABR)hearing tests were performed at 1st,3rd,7th and 14th days after noise exposure.On the 14th day after the hearing test,the mice were killed and the loss of hair cells was observed by immunofluorescent staining.Results:There was no significant change in ABR threshold in the blank control group.On the 1st day after noise exposure in 96 dB,100 dB,105 dB and 110 dB groups,all frequency thresholds were increased(P<0.05),and high frequency hearing thresh-olds were significantly higher than low frequency.On the 14th day of noise exposure,the hearing threshold of the 96 dB group re-covered to the pre-exposure level,and there was no statistical difference compared to that before noise exposure(P>0.05).The threshold changes of 100 dB group and 105 dB group were similar.The hearing thresholds of click and low frequency 8 kHz were partially recovered(P<0.05),while the thresholds of mid-frequency 16 kHz and high frequency 32 kHz were still at a high level(P<0.01).110 dB hearing loss is almost complete and irreversible.There was no defect of hair cells in 96 dB group,which was no significant difference compared to blank control group(P>0.05).Hair cell defects were observed in the middle and base turn of cochlea in the 100 dB group,105 dB group and 110 dB group,and the base turn damage was more obvious than the middle turn,and there was a difference compared to the blank control group(P<0.05),and the greater the noise intensity,the more hair cell damage.Conclusion:The animal model of noise-induced deafness was successfully established,and 96 dB group caused tempo-rary threshold shift without hair cell loss.The 100 dB group,105 dB group and 110 dB group showed permanent threshold shift with the loss of hair cells in the middle turn and base turn.