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Characterization of a synaptiform transmission between a neuron and a glial cell in the leech central nervous system
Author(s) -
Britz Frank C.,
Lohr Christian,
Schmidt Joachim,
Deitmer Joachim W.
Publication year - 2002
Publication title -
glia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.954
H-Index - 164
eISSN - 1098-1136
pISSN - 0894-1491
DOI - 10.1002/glia.10062
Subject(s) - neuron , biology , neuroscience , neurotransmission , leech , hirudo medicinalis , interneuron , neuroglia , nervous system , membrane potential , synapse , reversal potential , central nervous system , electrophysiology , inhibitory postsynaptic potential , patch clamp , biochemistry , receptor , world wide web , computer science
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 Ca 2+ /Mg 2+ concentration ratio. The results suggest that Leydig neuron activity leads to a Ca 2+ ‐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. GLIA 38:215–227, 2002. © 2002 Wiley‐Liss, Inc.