Kitahara Tadashi, Nakagawa Aya, Fukushima Munehisa, Horii Arata, Takeda Noriaki, Kubo Takeshi
Department of Otolaryngology and Sensory Organ Surgery, Osaka University Graduate School of Medicine, Japan.
Acta Otolaryngol. 2002 Sep;122(6):620-6. doi: 10.1080/000164802320396295.
In order to elucidate the role of the vestibulocerebellar neural circuits during two-stage bilateral labyrinthectomy (BL) we examined Fos-like immunoreactive (-LIR) neurons as a marker of neural activation in the rat brainstem after BL and the projections of these neurons into the vestibulocerebellum using retrograde tracing and immunohistochemical techniques. Simultaneous BL did not show any Fos expression in the medial vestibular nucleus (MVe). However, with an interval of > 6 h between the two stages of BL, Fos-LIR neurons were induced in the ipsilateral (ipsi-) MVe of the side operated on second, partially projecting into the ipsi-vestibulocerebellum. A previous study demonstrated that some of the unilateral labyrinthectomy-induced Fos-LIR neurons in the ipsi-MVe projected into the ipsi-vestibulocerebellum and inhibited the contra-MVe neurons, resulting in the restoration of the right-left balance. Taken together with our present data, it is suggested that some of the labyrinthectomy-induced Fos expression in the ipsi-MVe is representative of a switch-on signal for the vestibulo-cerebello-vestibular inhibitory neural circuits, which remain turned off after symmetrical lesions such as simultaneous BL but are turned on after severe asymmetrical lesions in order to restore the balance.
为了阐明两阶段双侧迷路切除术（BL）过程中前庭小脑神经回路的作用，我们使用逆行追踪和免疫组织化学技术，检测了BL后大鼠脑干中作为神经激活标志物的Fos样免疫反应性（-LIR）神经元，以及这些神经元向前庭小脑的投射。同时进行的BL在内侧前庭核（MVe）中未显示任何Fos表达。然而，在BL的两个阶段之间间隔>6小时时，在第二次手术侧的同侧（ipsi-）MVe中诱导出Fos-LIR神经元，部分投射到同侧前庭小脑。先前的一项研究表明，同侧MVe中一些单侧迷路切除术诱导的Fos-LIR神经元投射到同侧前庭小脑并抑制对侧MVe神经元，从而恢复左右平衡。结合我们目前的数据，提示同侧MVe中一些迷路切除术诱导的Fos表达代表前庭-小脑-前庭抑制性神经回路的开启信号，该回路在同时进行的BL等对称性损伤后保持关闭，但在严重不对称损伤后开启以恢复平衡。
