Britz Frank C, Lohr Christian, Schmidt Joachim, Deitmer Joachim W
Abteilung für Allgemeine Zoologie, FB Biologie, Universität Kaiserslautern, Germany.
Glia. 2002 May;38(3):215-27. doi: 10.1002/glia.10062.
The cross-talk between neurons and glial cells is receiving increased attention because of its potential role in information processing in nervous systems. Stimulation of a single identifiable neuron, the neurosecretory Leydig interneuron in segmental ganglia of the leech Hirudo medicinalis, which modulates specific behaviors in the leech, evokes membrane hyperpolarization directly in the giant glial cell (Schmidt and Deitmer. Eur J Neurosci 11:3125-3133, 1999). We have studied the neuron-to-glia signal transmission in the voltage-clamped giant glial cell to determine whether this interaction exhibits properties of a chemical synapse. The glial response had a mean latency of 4.9 s and was dependent on the action potential frequency; the glial cell responded to as few as five Leydig neuron action potentials in 50% of the trials. The glial current was sustained for minutes during repetitive Leydig neuron activity without any sign of desensitization. The current was sensitive to tetraethylammonium, and its reversal potential of -78 mV shifted with the external K+ concentration. The glial response increased with the duration of the neuronal action potentials and was sensitive to the external Ca2+/Mg2+ concentration ratio. The results suggest that Leydig neuron activity leads to a Ca2+-dependent release of transmitter from the neuronal dendrites, evoking an K+ outward current in the giant glial cell, implying a synapse-like transmission between a neuron and a glial cell.
由于神经元与神经胶质细胞之间的相互作用在神经系统信息处理中具有潜在作用，因此受到越来越多的关注。刺激单个可识别的神经元，即药用水蛭节段神经节中的神经分泌性莱迪希中间神经元，该神经元可调节水蛭的特定行为，可直接在巨大神经胶质细胞中诱发膜超极化（施密特和戴特默。《欧洲神经科学杂志》11:3125 - 3133，1999）。我们研究了电压钳制的巨大神经胶质细胞中神经元到神经胶质细胞的信号传递，以确定这种相互作用是否表现出化学突触的特性。神经胶质细胞的反应平均潜伏期为4.9秒，且依赖于动作电位频率；在50%的试验中，神经胶质细胞对低至5个莱迪希神经元动作电位有反应。在莱迪希神经元重复活动期间，神经胶质电流持续数分钟，没有任何脱敏迹象。该电流对四乙铵敏感，其 - 78 mV的反转电位随外部K⁺浓度而变化。神经胶质细胞的反应随神经元动作电位的持续时间增加，并且对外部Ca²⁺/Mg²⁺浓度比敏感。结果表明，莱迪希神经元的活动导致神经元树突中递质的Ca²⁺依赖性释放，在巨大神经胶质细胞中诱发K⁺外向电流，这意味着神经元与神经胶质细胞之间存在类似突触的传递。
