Mechanisms of glutamate release from astrocytes

• Published in: Neurochemistry international 2008-01, Vol.52 (1-2), p.142-154
• Main Authors: Malarkey, Erik B., Parpura, Vladimir
• Format: Article
• Language: English
• Subjects: Amino Acid Transport System X-AG - metabolism; Animals; Anion channels; Astrocytes - metabolism; Biological and medical sciences; Calcium - metabolism; Connexin “hemichannels”; Exocytosis; Fundamental and applied biological sciences. Psychology; Glutamate release; Glutamic Acid - metabolism; Humans; Ion Channels - metabolism; P2X receptors; Receptors, Purinergic P2 - metabolism; Receptors, Purinergic P2X7; Transporters; Vertebrates: nervous system and sense organs
• ISSN: 0197-0186; 1872-9754
• DOI: 10.1016/j.neuint.2007.06.005

Astrocytes can release the excitatory transmitter glutamate which is capable of modulating activity in nearby neurons. This astrocytic glutamate release can occur through six known mechanisms: (i) reversal of uptake by glutamate transporters (ii) anion channel opening induced by cell swelling, (iii) Ca2+-dependent exocytosis, (iv) glutamate exchange via the cystine–glutamate antiporter, (v) release through ionotropic purinergic receptors and (vi) functional unpaired connexons, “hemichannels”, on the cell surface. Although these various pathways have been defined, it is not clear how often and to what extent astrocytes employ different mechanisms. It will be necessary to determine whether the same glutamate release mechanisms that operate under physiological conditions operate during pathological conditions or whether there are specific release mechanisms that operate under particular conditions.