A new release from astrocytes (original) (raw)

Glia

Nature Reviews Neuroscience volume 5, page 516 (2004)Cite this article

Bezzi et al. showed that astrocytes in the rat hippocampus express transcripts that code for the vesicular glutamate transporters VGLUT1 and VGLUT2, which are responsible for glutamate uptake into synaptic vesicles. Using immunogold cytochemistry and electron microscopy, the authors pinpointed the location of these molecules to vesicular organelles, which were observed in regions of astrocytic processes that impinged on neuronal structures. In some cases, astrocytic vesicles faced neuronal NMDA (_N_-methyl-D-aspartate) receptors at nearly synaptic distance. The vesicles also expressed cellubrevin — a member of the vesicular SNARE (v-SNARE) family of proteins, which regulate the fusion of exocytic vesicles with the plasma membrane

Next, the authors used cultured astrocytes to examine whether the vesicles underwent regulated exocytosis in response to group I metabotropic glutamate receptor (mGluR) activation. They observed the behaviour of the vesicles using total internal reflection fluorescence imaging, a technique that allows dynamic cellular processes to be visualized at high resolution. They labelled the cells with acridine orange, a dye that accumulates in acidic cellular compartments in a self-quenched state and produces a flash of fluorescence when it is released at the cell surface. The astrocytes were also engineered to express VGLUT1 or VGLUT2 tagged with enhanced green fluorescent protein. The authors showed that the mGluR agonist dihydroxyphenylglycine evoked flashes of fluorescence at the cell membrane, concomitant with the disappearance of some of the VGLUT-expressing vesicles.

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References

ORIGINAL RESEARCH PAPER

  1. Bezzi, P. et al. Astrocytes contain a vesicular compartment that is competent for regulated exocytosis of glutamate. Nature Neurosci. 7, 613–620 (2004)
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FURTHER READING

  1. Haydon, P. G. Glia: listening and talking to the synapse. Nature Rev. Neurosci. 2, 185–193 (2001)
    Article CAS Google Scholar
  2. Newman, E. A. New roles for astrocytes: regulation of synaptic transmission. Trends Neurosci. 26, 536–542 (2003)
    Article CAS Google Scholar

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Wood, H. A new release from astrocytes.Nat Rev Neurosci 5, 516 (2004). https://doi.org/10.1038/nrn1439

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