Feng K, Zhang S H, Zhang Y C
Department of Physiology, Capital University of Medical Sciences, Beijing 100052, China.
Zhongguo Yi Xue Ke Xue Yuan Xue Bao. 2001 Oct;23(5):509-14.
To investigate the effects of afferent excitatory inputs from skin on the excitability of Mauthner cell (M cell) of crucian carp.
Multiple-site intracellular recordings on the soma and the ventral dendrite (VD) of M cell and direct current stimulation on the skin surface of the fish's trunk were employed.
Direct stimulation of the skin evoked 3 groups of compound excitatory postsynaptic potentials (EPSPs) on soma and VD of M cell. Group a EPSP had the lowest amplitude (< or = 0.35 mV), which was insensitive to high-frequency stimulation. It had the shortest latency (mean 1.9 ms) and could be recorded on the soma and the proximal end of VD. Group b EPSP had the highest amplitude (< or = 9.7 mV), which was increased when the recording electrode was moved from the soma to the distal end of VD. The latency of Group b (mean 4.5 ms) was shorter than that of Group c, but longer than that of Group a. We firstly found that action potential could be induced on the basis of Group b in M cell by skin stimulation. Group c EPSP was our new finding, which could only be evoked by higher intensity (noxious) stimulus (> or = 100 V). It had the longest latency (mean 13.5 ms) with amplitude between those of a and b, and was very sensitive to high frequency stimulation. All the three groups of EPSPs were superimposed with spike-like transient potentials, which were believed to be the sign of electrical synapse activities.
(1) Action potential can be induced on M cell by skin stimulation, which is in controversy with previous reports; (2) the noxious skin stimulation can induce a late EPSP (Group c) in M cell; (3) the neural pathway projecting from skin to M cell is composed of a set of neuronal chains with different number of synaptic relays, in which short chains projected concentrically to the soma and the proximal part of VD, while long chains projected mainly to the distal part of VD; (4) both electrical and chemical synapses may exist in short and long pathways.
研究皮肤传入性兴奋性输入对鲫鱼Mauthner细胞（M细胞）兴奋性的影响。
采用对M细胞的胞体和腹侧树突进行多位点细胞内记录以及对鱼体躯干部皮肤表面进行直流电刺激的方法。
直接刺激皮肤可在M细胞的胞体和腹侧树突上诱发3组复合兴奋性突触后电位（EPSP）。a组EPSP幅度最低（≤0.35 mV），对高频刺激不敏感。其潜伏期最短（平均1.9 ms），可在胞体和腹侧树突近端记录到。b组EPSP幅度最高（≤9.7 mV），当记录电极从胞体移向腹侧树突远端时其幅度增加。b组潜伏期（平均4.5 ms）短于c组，但长于a组。我们首次发现皮肤刺激可在M细胞上基于b组诱发动作电位。c组EPSP是我们的新发现，仅能由更高强度（有害）刺激（≥100 V）诱发。其潜伏期最长（平均13.5 ms），幅度介于a组和b组之间，且对高频刺激非常敏感。所有这三组EPSP均叠加有尖峰样瞬态电位，据信这是电突触活动的标志。
（1）皮肤刺激可在M细胞上诱发动作电位，这与先前报道存在争议；（2）有害皮肤刺激可在M细胞中诱发晚期EPSP（c组）；（3）从皮肤投射到M细胞的神经通路由一组具有不同突触中继数量的神经元链组成，其中短链向胞体和腹侧树突近端同心投射，而长链主要向腹侧树突远端投射；（4）在短通路和长通路中可能均存在电突触和化学突触。
