Nicolas-Puel C, Durrieu J P, Lenoir M, Tran Ba Huy T, Uziel A, Puel J L
INSERM U.254, Université de Montpellier, Laboratoire de Neurobiologie de l'Audition-Plasticité Synaptique, CHR Saint Charles, France.
Hear Res. 1996 Oct;100(1-2):181-91. doi: 10.1016/0378-5955(96)00112-8.
This study investigates whether auditory brainstem responses (ABRs) can be used to assess the functioning of electrically stimulated cochleas. Electrically evoked auditory brainstem responses (EABRs) were recorded in guinea pigs with normal hearing and guinea pigs deafened by amikacin, a powerful ototoxic antibiotic, combined with diuretic aminooxyacetic acid (AOAA). Two different types of EABRs were observed in normal animals, depending on the electrical pulse intensity applied to the round window: long-latency brainstem responses were evoked by low stimulation intensities, short-latency brainstem responses by high intensities. The absence of effect of strychnine applied intracochlearly ruled out the possibility of medial efferents being involved in these responses. Conversely, an intracochlear application of tetrodotoxin (TTX), an Na(+)-channel blocker, resulted in the disappearance of both types of responses, attesting that the sites activated by the electrical stimulation were located within the cochlea. In AOAA/ amikacin poisoned cochleas, in which most of the hair cells were missing with apparently normal ganglion neurons, the long-latency brainstem responses evoked by low intensities were completely lacking. These findings suggest that low currents applied to the round window of the guinea pig cochlea primarily activate the hair cells, the neurons being directly excited at higher intensities.
本研究调查了听觉脑干反应（ABR）是否可用于评估电刺激耳蜗的功能。在听力正常的豚鼠以及因强力耳毒性抗生素阿米卡星联合利尿剂氨氧乙酸（AOAA）致聋的豚鼠中记录电诱发听觉脑干反应（EABR）。在正常动物中观察到两种不同类型的EABR，这取决于施加于圆窗的电脉冲强度：低刺激强度诱发长潜伏期脑干反应，高刺激强度诱发短潜伏期脑干反应。耳蜗内应用士的宁无效，排除了内侧传出神经参与这些反应的可能性。相反，耳蜗内应用河豚毒素（TTX），一种钠通道阻滞剂，导致两种类型的反应均消失，证明电刺激激活的部位位于耳蜗内。在AOAA/阿米卡星中毒的耳蜗中，大部分毛细胞缺失而神经节神经元明显正常，低强度诱发的长潜伏期脑干反应完全缺失。这些发现表明，施加于豚鼠耳蜗圆窗的低电流主要激活毛细胞，而神经元在较高强度时被直接兴奋。
