脉冲噪声暴露后大鼠下丘核生长相关蛋白-43表达的研究

目的 探讨脉冲噪声暴露对大鼠下丘核生长相关蛋白-43(growth associated protein,Gap-43)表达的影响.方法 SPF级成年雄性SD大鼠30只,随机分为正常对照组6只、噪声暴露组24只,正常对照组不接受噪声暴露,噪声暴露组接受脉冲噪声暴露,噪声平均压力峰值156 dB SPL,脉宽0.25 ms,单次暴露6 s,共暴露50次.于噪声暴露前及暴露后3、7、14、28 d分别测试对照组及噪声暴露组(每个时间点6只)大鼠听性脑干反应(auditory brainstem response,ABR)阈值;然后取双侧下丘进行免疫组化染色,通过灰度值检测各组大鼠下丘Gap-43蛋白表达水平.结果 噪声暴露后各组大鼠ABR反应阈显著高于正常组(P<0.01),噪声暴露后14、28 d组ABR阈值显著低于暴露后3 d组(P<0.05);噪声暴露后各组大鼠双侧下丘Gap-43蛋白表达显著高于正常组(P<0.01),暴露后28 d组大鼠下丘Gap-43蛋白表达显著低于暴露后3 d组(P<0.05).结论 脉冲噪声暴露可导致大鼠ABR反应阈显著升高,下丘Gap-43蛋白高表达;脉冲噪声暴露后不同时间大鼠ABR阈值升高和下丘Gap-43蛋白高表达的变化规律可能与听皮层突触重塑有关.

Expression of Growth Associated Protein 43 in Inferior Colliculus of Rats at Different Times after Impulse Noise Exposur

Objective To investigate the effect of impulse noise expose on the expression of growth associated protein 43(Gap-43) in inferior colliculus in rat.Methods SPF grade Male SD rats were randomly divided into 5 groups.The normal control group received noise exposure.The model groups received an averange impulse noise exposure of 156 dB SPL with a pulse duration of 0.23 ms, once for 6 s, for 50 times.Auditory brainstem responses (ABRs) were measured before and 3,7,14, and 28 d after noise exposure with tone pips of 2,4,8,16, and 32 kHz, from 20 to 110 dB SPL.Bilateral inferior colliculus of rats in the model groups was collected and treated by immunohistochemical staining.Gap-43 expression of rats in different groups was measured by determining the gray value of inferior immunohistochemical images.Results After noise exposure, ABRs threshold in the model groups were significantly higher than those of in the normal group (P<0.05 or P<0.01).ABRs threshold at 14 and 28 days after noise exposure were significantly lower than 3 days after impulse exposure (P<0.05).Expression of Gap-43 in inferior colliculus was significantly up-regulated in the noise exposed groups compared with the normal group (P<0.05 or P<0.01).Expression of Gap-43 was significantly down-regulated 28 days after noise expose compared with 3 days after noise expose(P<0.05).Conclusion Impulse noise exposure leads to significant elevation of ABR thresholds and up-regulation of Gap-43 expression in inferior colliculus.Impulse noise exposure may induce auditory cortex prominent remodeling.