Response of oligodendrocytes to glutamate and gamma-aminobutyric acid in the intact mouse optic nerve.
The electrophysiological response to glutamate and gamma-aminobutyric acid (GABA) is determined in oligodendrocytes of the isolated intact mouse optic nerve, identified by their characteristic morphology following iontophoretic injection with horseradish peroxidase (HRP). In this study, mature myelin-forming oligodendrocytes are shown for the first time to respond to glutamate and GABA in situ, by a 2-3 mV depolarization. Morphologically homogeneous oligodendrocytes exhibit a heterogeneous response to glutamate and GABA; some cells respond to both excitatory amino acids, whereas others respond to one but not the other, and some oligodendrocytes do not respond to either. Oligodendrocytes uniformly depolarize in elevated [K+]o and it is concluded that the effect of glutamate and GABA is not mediated by an increase in [K+]o released from axons or astrocytes. The oligodendrocyte response to amino acids may be important in axon-to-oligodendrocyte signalling at the nodes of Ranvier.
Sherrington School of Physiology, U.M.D.S., St. Thomas's Hospital, London, UK.
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D000818:Animals; D004594:Electrophysiology; D005971:Glutamates / Q000494:pharmacology*; D018698:Glutamic Acid; D066298:In Vitro Techniques; D008564:Membrane Potentials / Q000187:drug effects; D051379:Mice; D008807:Mice, Inbred BALB C; D009474:Neurons / Q000187:drug effects*; D009836:Oligodendroglia / Q000187:drug effects*; D009900:Optic Nerve / Q000166:cytology / Q000187:drug effects*; D005680:gamma-Aminobutyric Acid / Q000494:pharmacology*
D005971:Glutamates; D018698:Glutamic Acid; D005680:gamma-Aminobutyric Acid