光学方法二维成像前庭核神经元的突触传导

OPTICAL IMAGING OF THE SPATIOTEMPORAL PATTERNS OF THE NEURONAL ACTIVITY IN VESTIBULAR NUCLEUS

为探索前庭核神经元传导的时空二维特征 ,用吸光性电压敏感染料RH1 5 5染色新生小鼠的脑干切片 2 0min ,电刺激前庭神经 ,用光学记录膜电位技术成像前庭核的神经电活动。结果显示 ,电刺激前庭神经后光学记录显示前庭核出现神经电兴奋 ,在部分实验中观察到同侧及对侧前庭核的兴奋传导 ;前庭核神经兴奋有激发延迟和高峰延迟 ;所记录的光学信号具有光吸收波长特性 ,表明光学记录的可靠性 ;光学信号包括尖峰状快反应信号和持续较长时间的慢反应信号 ,所有兴奋信号被 2 0 μmol/L河豚毒 (特异性钠通道阻断剂 )不可逆性消除 ,表明快反应信号来源于钠通道介导的动作电位 ,慢反应信号被无钙液可逆性阻断 ,表明慢反应信号可能为兴奋性突触后电位。研究表明 。

To explore the spatiotemporal patterns of the neuronal excitatory propagation in vestibular nucleus, brainstem sections were prepared from postnatal 1～5 day mice, and stained with RH155, which was an light absorbent voltage sensitive dye, for 20 minutes. A multiple site optical recording system was used for optical imaging of the evoked responses after electrical stimulation of the vestibular nerve. After stimulation of the vestibular nerve, optical responses were revealed in the vestibular nucleus. There was propagation of excitation in both ipsilateral vestibular nucleus and contralateral vestibular nucleus after ipsilateral vestibular nerve stimulation. These optical signals were wave length dependent. The optical signals consisted of two components: the spike like fast signal and long duration slow signal. All the responses were abolished by 20μmol/L tetrodotoxin (TTX). The effect of TTX was irreversible. The slow signals were entirely eliminated after the application of Ca 2+ free solution. The effect of Ca 2+ free solution was reversible. These results suggested that the slow signal might be postsynaptic excitation potential. The present study indicated that the use of optical recording to reveal visually the synaptic transmission of afferent input in vestibular nucleus in the brainstem was feasible.