脉冲噪声暴露后大鼠频率特异性听性脑干反应变化特点及意义

Effect of Impulse Noise on the Frequency-Specific Auditory Brainstem Response in Rat

目的探讨脉冲噪声暴露后不同时间大鼠频率特异性听性脑干反应变化特点及意义。方法成年SD大鼠50只分为5组:正常组及脉冲噪声暴露后3、7、14、28天组,每组10只。脉冲噪声条件为:平均压力峰值为156dBSPL,脉宽0.25ms,暴露50次,分别于暴露前后对大鼠行ABR检测,刺激声为短音(tonepip),频率范围为2～32kHz。结果①正常大鼠2、4、8、16、32kHz的平均听阈分别为68.5±2.67、58.2±2.58、39.3±3.33、37.5±2.95、37.3±3.60dBSPL;②与脉冲噪声暴露前相比较,暴露后各组2、4、8、16、32kHzABR阈值均明显提高,差异有统计学意义(P<0.05),其中高频阈移的幅度较低频阈移幅度大;在暴露后恢复第7天时,各频率ABR阈值有所恢复,第14天时恢复明显,第28天时与第14天接近。结论脉冲噪声暴露后大鼠频率特异性听性脑干反应阈值升高,第7天后开始有所恢复,可为后期进一步研究听觉中枢可塑性建立稳定有效的急性声损伤动物模型。

Objective To investigate the characteristic changes of frequency--specific auditory brainstem responses （ABRs） after impulse noise exposure in rat. Methods Fifty adult SD rats were divided into 5 groups which were： normal group, 3 days post--exposure group, 7 days post--exposure group, 14 days post--exposure group and 28 days post--exposure group with 10 rats in each group. Impulse noise at 156 dB SPL with 50 pulses （pulse duration was 0.25 ms） was used for the exposure. Tone pips at different frequencies ranging from 2 kHz to 32 kHz were used for ABR induction. ABR were detected pre--exposure, 3 days, 7 days, 14 days and 28 days after the exposure, respectively. Results 1. In the normal group, ABR average thresholds at 2, 4, 8, 16, 32 kHz were 68.5±2.67, 58.2±2.58, 39.3±3.33, 37.5±2.95 and 37.3±3.6 dB SPL, respectively. 2. Comparing to those of pre-exposure, AI3R thresholds at different frequencies in all exposed groups significantly elevated （P〈0.05） with a recovery at day 7 post--exposure and an obvious recovery at day 14, however there were no further recovery after day 14 post--exposure. Conclusion ABRs stimulated by frequency--specific tone pip could reflect the auditory char- acteristic changes after impulse noise exposure in rat, thus providing an effective animal model for acute acoustic trauma.