实验性冲击波负压暴露后豚鼠耳蜗基底膜AChE和SDH活性的变化

Activity changes of AChE and SDH in the cochlear basilar membrane of guinea pigs exposed to blast underpressure

目的探讨冲击波负压(BUP)暴露对豚鼠耳蜗基底膜乙酰胆碱酯酶(AChE)和琥珀酸脱氢酶(SDH)活性的影响。方法中等强度BUP重复暴露3次后2h-3d检测豚鼠听性脑干反应(ABR)阈值,然后处死并应用酶组织化学技术观察其耳蜗基底膜两种酶的活性产物的变化。结果负压峰值为-44．5 kPa--48．8 kPa的BUP暴露后2h,耳蜗基底膜外毛细胞下神经末梢区域AChE活性产物明显减少,在负压暴露后24h和3d时有所恢复,但仍低于正常对照组。基底膜SDH活性下降主要发生于外毛细胞,且以第二转第三排最为明显;BUP暴露后2h活性下降幅度最大, 至24h和3d时有所恢复。上述两种酶活性产物的变化,与动物的ABR阈移幅度变化是一致的。结论 BUP暴露后豚鼠耳蜗基底膜的AChE和SDH活性有不同程度的下降,这可能是造成BUP暴露后听力损失的一个主要原因。

Objective To evaluate the effects of blast underpressure （BUP） exposure on acetylcholine esterase （ACHE） and succinate dehydrogenase （SDH） in the chealear basilar membrane of guinea pigs. Methods Assessment of auditory function was made by auditory brainstem response （ABR） with subsequent t of the AChE and SDH activity staining density in chealear hair cells using enzymatic histochemistry. Results , Light microscopy revealed that the AChE activity products appeared in the areas arounding efferent nerve endings in contact with the base of the outer hair cells decreased obviously after two hours following exposure to moderate BUP at peak underpressure of between -44.5 kPa and -48.8 kPa for three times. The activity of the enzyme increased at 24 hours and three days postexposure but it was still less than that of control groups. The SDH staining showed that the enzyme activity decreased mainly in the second and third rows of outer hair cells in the second cochlea turn occurved as early as two hours postexposure. The activity staining recovered partly 24 hours and three days postexposure. The changes of the two enzyme activity coincided with the ABR threshold shifts. Conclusion The moderate BUP exposure can decrease the activity of AChE and SDH which may be a main cause of hearing loss following exposure to BUP.