Morphological evidence for vesicular glutamate release from astrocytes.
There is now growing evidence that astrocytes, like neurons, can release transmitters. One transmitter that in a vast number of studies has been shown to be released from astrocytes is glutamate. Although asytrocytic glutamate may be released by several mechanisms, the evidence in favor of exocytosis is most compelling. Astrocytes may respond to neuronal activity by such exocytotic release of glutamate. The astrocyte derived glutamate can in turn activate neuronal glutamate receptors, in particular N-methyl-D-aspartate (NMDA) receptors. Here we review the morphological data supporting that astrocytes possess the machinery for exocytosis of glutamate. We describe the presence of small synaptic-like microvesicles, SNARE proteins and vesicular glutamate transporters in astrocytes, as well as NMDA receptors situated in vicinity of the astrocytic vesicles.
Bergersen
L H
LH
Department of Anatomy, Institute of Basic Medical Sciences, University of Oslo, POB 1105 Blindern, 0317 Oslo, Norway. l.h.bergersen@medisin.uio.no
Gundersen
V
V
D000818:Animals; D001253:Astrocytes / Q000378:metabolism* / Q000648:ultrastructure; D001921:Brain / Q000378:metabolism* / Q000648:ultrastructure; D002450:Cell Communication / Q000502:physiology; D005089:Exocytosis / Q000502:physiology*; D018698:Glutamic Acid / Q000378:metabolism*; D006801:Humans; D009474:Neurons / Q000378:metabolism; D016194:Receptors, N-Methyl-D-Aspartate / Q000378:metabolism; D050600:SNARE Proteins / Q000378:metabolism; D022142:Secretory Vesicles / Q000378:metabolism* / Q000648:ultrastructure; D050496:Vesicular Glutamate Transport Proteins / Q000378:metabolism
D016194:Receptors, N-Methyl-D-Aspartate; D050600:SNARE Proteins; D050496:Vesicular Glutamate Transport Proteins; D018698:Glutamic Acid