INTRACELLULAR AND EXTRACELLULAR ELECTROPHYSIOLOGY OF NIGRAL DOPAMINERGIC-NEURONS .2. ACTION-POTENTIAL GENERATING MECHANISMS AND MORPHOLOGICAL CORRELATES
INTRACELLULAR AND EXTRACELLULAR ELECTROPHYSIOLOGY OF NIGRAL DOPAMINERGIC-NEURONS .2. ACTION-POTENTIAL GENERATING MECHANISMS AND MORPHOLOGICAL CORRELATES
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DOI：
10.1016/0306-4522(83)90136-7
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发表时间：
1983-01-01
期刊：
影响因子：
3.3
通讯作者：
BUNNEY, BS
中科院分区：
文献类型：
--
作者：
GRACE, AA;BUNNEY, BS
从确定的黑质多巴胺神经元的细胞内记录显示，它们的电位由4个组成部分：缓慢去极化，初始段锋电位，体树突锋电位和后超极化。通过将细胞内和细胞外记录技术与使用荧光黄的细胞内注射的解剖学研究相结合，尝试将这些电位中的每一个定位到各种神经元隔室。荧光黄注射证明记录的多巴胺神经元具有直径为12-30 μ m的锥体或多边形索马，具有3-6个厚的主要树突，其在分叉之前从索马延伸10-50 μ m。轴突似乎从距索马15-30 μ m的主要树突升起。基于这一解剖结构，电生理研究结果表明：慢去极化是一种起搏器样传导，最可能位于躯体区域，起始节段锋电位是一种低阈值锋电位，可能位于轴突丘;体树突棘波是随着去极化而快速变化的长持续时间的棘波，具有高阈值并局限于树枝状区域。动作电位随后被长时间的后超极化终止。尖峰的产生可以通过在索马的缓慢去极化来启动，从而触发低阈值轴突丘中的尖峰，该尖峰然后在已经去极化的索马上传播以触发树突尖峰。多巴胺神经元可以在电生理学和形态学上划分为子成分，每个子成分与尖峰和特定的离子电流相关。动作电位的高阈值树突成分表现出快速失活与去极化，并发生在一个相当窄的范围内的膜极化。这种有限的动作电位产生范围可能在控制树突多巴胺释放和/或调节多巴胺能神经元之间的电耦合中是重要的。
Intracellular recordings from identified nigral dopamine neurons in the rat reveal that their potentials are composed of 4 components: a slow depolarization, an initial segment spike, a somatodendritic spike and an afterhyperpolarization. By combining intracellular and extracellular recording techniques with anatomical studies using intracellular injections of Lucifer yellow, an attempt was made to localize each of these potentials to various neuronal compartments. Lucifer yellow injections demonstrated that the dopamine neurons recorded have a pyramidal or polygonal shaped soma, 12-30 .mu.m in diameter, with 3-6 thick major dendrites which extend 10-50 .mu.m from the soma before bifurcating. The axon appears to rise from a major dendrite 15-30 .mu.m from the soma. Based on this anatomical configuration, results from the electrophysiological studies suggest the following conclusions; the slow depolarization is a pacemaker-like conductance most likely localized to the somatic region; the initial segment spike is a low-threshold spike probably located at the axon hillock; the somatodendritic spikes are long duration spikes that rapidly inactivate with depolarization, have a high threshold and are localized to the dendritic regions. The action potential is then terminated by a long duration afterhyperpolarization. Spike generation may be initiated by a slow depolarization at the soma, triggering a spike in the low-threshold axon hillock which then spreads across the already-depolarized soma to trigger the dendritic spike. Dopamine neurons can be compartmentalized electrophysiologically and morphologically into subcomponents, each associated with spikes and specific ionic currents. The high threshold dendritic component of the action potential demonstrates rapid inactivation with depolarization, and occurs over a rather narrow range of membrane polarization. This limited range of action potential generation may be important in control of dendritic dopamine release and/or modulation of electrical coupling between dopaminergic neurons.