脑震荡前后大鼠听力及耳蜗形态变化

Changes of hearing and cochlear morphology in rats with cerebral concussion

目的观察脑震荡前后Wistar大鼠畸变产物耳声发射(distortion product otoacoustic emissions,DPOAE)、听性脑干反应(auditory brainstemresponses,ABR)阈值及耳蜗形态的变化。方法40只健康雄性Wistar大鼠随机分成4组,分别为撞击前组,撞击后30分钟组,撞击后1小时组以及撞击后1天组,各组10只。选用0.5、0.7、1、1.4、2、3、4、6及8kHz共9个频率点进行DPOAE(f2/f1=1.2,L1=65dBSPL,L2=55dBSPL)幅值测试,同时进行ABR阈值检测。并进行耳蜗毛细胞及周围组织形态学观察。结果撞击前测得的ABR反应阈值分别与撞击后30分钟、撞击后1小时及撞击后1天比较,反应阈值升高,差异有显著性意义(P<0.05)。DPOAE测试显示,撞击前分别与撞击后30分钟、1小时和1天比较,在2kHz时其幅值均有显著性差异(P<0.05),即撞击后出现DPOAE幅值下降。这一结果与形态学结果相吻合。结论撞击后DPOAE幅值在频率2kHz时下降,ABR反应阈值和DPOAE检测幅值的改变说明脑震荡对耳蜗外毛细胞有一定的损害。

OBJECTIVE To observe the changes of distortion product otoacoustic emissions （DPOAE）,auditory brainstem responses （ABR） and cochlear function in different periods about the Wistar rats of cerebral concussion. METHODS Forty healthy male Wistar rats were divided into 4 groups with 10 rats each groupnormal period, 30 minutes after rammed, 1 hour after rammed, and 1 day after rammed. The DPOAE audiogram 0.5,0.7,1,1.4,2,3,4,6,8kHz f2/ f1=1.2, f1=65dBSPL, f2=55dBSPL were measured and analyzed in the three circumstances. At the same time the threshold of ABR were measured. The morphological changes of cochlear hair cells and their adjacent tissues were observed under the optical microscope and the scanning electron microscope. RESULTS The increased threshold of ABR were observed after rammed （P〈0.05） .The statistically significant decreased amplitude of DPOAE was observed at 2 kHz after rammed at 1 hour and 1 day （P〈0.05）. However, no difference was observed at other frequencies （P〉0.05）. Fewer changes were observed at 30 minutes after rammed （P〉0.05）. The morphological changes were observed in the cochlea. Moreover, the changes of cochlear tissues under the optical microscope wasa lot of akaryotes were found in the blood capillary of cartilaginous tissue in the rats of 30 minutes after rammed; a great quantity inflammatory cells were observed in the blood capillary of cartilaginous tissue in the rats of 1 day rammed. The changes of morphology coincided with the results of DPOAE. CONCLUSION Outer hair cells may be injured by cerebral concussion and the changes were showed by DPOAE and ABR.