Glial regulation of nonsynaptic extracellular glutamate in the substantia nigra.

Glia

Laboratory of Neurobiology and Experimental Neurology, Department of Physiology, University of La Laguna, La Laguna, Tenerife, Canary Islands, Spain.

Published: January 2005

AI Article Synopsis

  • GLU is the primary neurotransmitter in the brain, with a newfound focus on an extracellular nonsynaptic GLU (EnS-GLU) pool that releases from glial cells and affects distant neurons.
  • Research in the rat substantia nigra (SN) indicates that this EnS-GLU pool increases with calcium influx during cell depolarization, and is influenced by glial cell activity.
  • The study also shows that glutamine boosts GLU levels and highlights that the interactions between various glutamate receptors can modulate the EnS-GLU pool, suggesting it plays a role in long-distance communication in the brain.

Article Abstract

GLU is the main neurotransmitter in the brain, where it induces a synaptic excitatory action. There is recent evidence for an extracellular nonsynaptic GLU (EnS-GLU) pool in different brain nuclei that, released from glial cells, may act on extrasynaptic GLU receptors of cells located far from the position in which it was released. In the present work, the EnS-GLU pool was studied with microdialysis in the rat substantia nigra (SN). We observed an EnS-GLU pool that increased in a Ca2+-dependent manner during cell depolarization. The selective alteration of with methionine sulfoximide (MSO) and fluorocitrate induced marked modifications in EnS-GLU suggesting that EnS-GLU is dependent on glial cells. Glutamine administration increased GLU, suggesting that neurons are also involved in EnS-GLU modulation. GLU administered in the rostral SN showed a long-distance diffusion to the caudal SN. The ionotropic GLU receptors agonist N-methyl-D-aspartate and kainate and the metabotropic GLU receptors agonist ACPD increased EnS-GLU and decreased extracellular glutamine. Taken together, these data indicate that nigral glia releases GLU, which probably performs a volume transmitter role.

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Source
http://dx.doi.org/10.1002/glia.20100DOI Listing

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