Negandhi Jaina, Harrison Adrienne L, Allemang Cullen, Harrison Robert V
Auditory Science Laboratory, Neuroscience and Mental Health Program, The Hospital for Sick Children, 555 University Ave., Toronto, M5G 1X8 Canada.
Auditory Science Laboratory, Neuroscience and Mental Health Program, The Hospital for Sick Children, 555 University Ave., Toronto, M5G 1X8 Canada; Department of Otolaryngology-Head and Neck Surgery, Hospital for Sick Children and the University of Toronto, 190 Elizabeth St., Rm 3S-438, R. Fraser Elliott Building, Toronto, M5G 2N2 Canada.
Hear Res. 2014 Sep;315:34-9. doi: 10.1016/j.heares.2014.06.002. Epub 2014 Jun 26.
The dynamics of cochlear excitotoxicity can be monitored from effects on the contralateral ear. After unilateral mechanical ablation of the cochlea (in a mouse model) we observed immediate elevations in auditory brainstem evoked response (ABR) thresholds in the contralateral ear. Threshold elevations peaked at 2-3 h post ablation, and returned to baseline levels after 5-6 h. These contralateral effects are initiated by cochlear afferent injury discharges most likely activating the olivocochlear efferent system. Six hours after cochlear injury, ABR thresholds were fully returned to pre-lesion baseline levels and remained normal for up to 10 days of monitoring. We have confirmed that our cochlear ablation procedure increases short-term activity levels in the auditory brainstem and midbrain using c-fos labelling. The study provides insight into the dynamics of glutamate excitotoxicity, a pathological process directly related to acute tinnitus after acoustic trauma, and more generally implicated in many types of brain injury and neuro-degenerative disease.
可通过观察对侧耳的变化来监测耳蜗兴奋性毒性的动态过程。在对耳蜗进行单侧机械消融后（小鼠模型），我们观察到对侧耳的听觉脑干诱发电位（ABR）阈值立即升高。阈值升高在消融后2 - 3小时达到峰值，并在5 - 6小时后恢复到基线水平。这些对侧效应最有可能是由耳蜗传入神经损伤放电激活橄榄耳蜗传出系统引发的。耳蜗损伤6小时后，ABR阈值完全恢复到损伤前的基线水平，并且在长达10天的监测期内保持正常。我们已通过c - fos标记证实，我们的耳蜗消融程序会增加听觉脑干和中脑的短期活动水平。这项研究为谷氨酸兴奋性毒性的动态过程提供了见解，谷氨酸兴奋性毒性是一种与声学创伤后急性耳鸣直接相关的病理过程，并且在许多类型的脑损伤和神经退行性疾病中普遍存在。
