Mechanisms of glutamate release from astrocytes

Published on June 29, 2011 Reviewed on May 1, 2020   49 min

Other Talks in the Series: Physiology and Pathophysiology of Neuroglia

0:00
My name is Vladimir Parpura. I will talk about various mechanisms of glutamate release from astrocytes, a subtype of glial cell in the nervous system.
0:13
Neuroglia was first time described in 1856 by the German neuropathologist Rudolf Virchow as a putty that binds nervous elements together, somewhat like cement that binds the bricks.
0:31
The Spanish neuroanatomist Santiago Ramon Y Cajal proposed that neuroglia, shown in dark brown in his drawing, have a more active role in the brain, since their position at the interface between blood vessels, shown in A, and neurons, shown in C and D. We know today that the gold sublimate stain that he used targeted intermediate filaments that consist mainly of glial fibrillary acidic protein abbreviated as GFAP, which is used today as an astrocytic marker.
1:07
This slide shows an image of purified cultures of astrocytes stained using indirect immunocytochemistry with an antibody against GFAP, shown in red. The cell nuclei shown in blue are stained using DAPI. Such cells in culture were instrumental in describing various mechanisms utilized by astrocytes for the release of the major excitatory transmitter glutamate as summarized in the next slide.
1:40
There are six known mechanisms of glutamate release from astrocytes, shown clockwise in the order of their discoveries, along with original references. 1, swelling induced opening of volume regulated anion channels. 2, reverse operation of excitatory amino acid transporters. 3, calcium dependent exocytosis. 4, the cysteine glutamate exchanger. 5, connexin hemichannels. And 6, the purinergic P2X7 receptors. I'll discuss each of these mechanisms, although not in order of their discoveries. I will start the discussion of glutamate release through plasma membrane transporters, such as the reversal of uptake by excitatory amino acid transporters, and exchange by the cysteine glutamate antiporter. Then I will follow up by a more detailed discussion of glutamate release through calcium dependent exocytosis. And finally I will discuss glutamate release through channels on the cell surface, such as anion channel opening induced by cell swelling, released ionotropic purinergic receptors, and by unpaired connexin.
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Mechanisms of glutamate release from astrocytes

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