迷走神经感觉输入诱发的鲫鱼Mauthner细胞胞内电位变化

Intracellular potential changes in crucian carps′ Mauthner cells evoked by vagal sensory inputs

实验运用微电极穿刺技术 ,初步探索了刺激鲫鱼右侧迷走神经在双侧Mauthner (M)细胞胞体诱发的胞内电位变化。结果表明 :( 1)直接刺激鲫鱼右侧迷走神经 ,可在同侧或对侧M细胞胞体记录到一种短潜伏期、长持续时间、分级的、复合的突触后电位 (postsynapticpotentials,PSPs)。此PSPs表现出明显的强度依从性和频率依赖性。 ( 2 )刺激迷走神经诱发的PSPs可使逆向锋电位的幅度降低。 ( 3 )肌注士的宁后 ,PSPs的幅度增高、平均持续时间增加、峰值前移 ,并且可爆发两个以上的动作电位。上述结果提示 :迷走神经到M细胞的通路可能是由长短不等的神经链群组成的 ,且此通路中不仅包含有兴奋性成分还包含有抑制性成分 ,而兴奋和抑制之间的相互关系可能起着调节M细胞兴奋性的作用。

In the present experiments, microelectrode recording technique was used to explore the electrophysiological properties of Mauthner cells (M cells) with stimuli applied to the right vagus. Direct stimulation of the right vagus evoked short latency, long lasting, graded, and complex postsynaptic potentials (PSPs) on both Mauthner cell bodies in crucian carp,which are stimulus strength and frequency dependent.The evoked PSPs reduced the amplitudes of the antidromic action potentials.After intramuscular injection of strychnine,both amplitude and averaged duration of the PSPs increased,on which two or more action potentials were superimposed.The results suggest that the afferent pathways from vagus to M cells are mediated by several neuron chains with different numbers of relayed synapses,and they may be excitatory and/or inhibitory in nature.Therefore vagus input would modulate the excitability of the M cells.