Glial Cells and the Synapse

Science's STKE  08 May 2001:
Vol. 2001, Issue 81, pp. tw3
DOI: 10.1126/stke.2001.81.tw3

Glia cells participate in the regulation of synaptic transmission by controlling neurotransmitter diffusion and concentration in the synaptic cleft. Two reports explore the role of glutamate and its receptors in this regulatory process (see the Perspective by Gallo and Chittajallu). To investigate the role of glial glutamate uptake, Oliet et al. took advantage of a substantial anatomical rearrangement between astrocytes and neurons in the hypothalamus during changes in reproductive state. During lactation, astrocyte ensheathment of synapses and, hence, glutamate removal are reduced, which leads to changes in the amplitude of evoked excitatory potential caused by activation of presynaptic metabotropic glutamate receptors. Glia cells express AMPA glutamate receptor subunits, the physiological role of which has been poorly understood. Iino et al. altered the function of Bergmann glia cells in the cerebellum by adding an AMPA receptor subunit that renders the channels calcium-impermeable. They observed major changes in the morphology of the glia cell specializations around the synapses: The glial envelopment around Purkinje cell dendritic spines became retracted. Removal of released glutamate was impaired and led to an unusual multiple climbing-fiber innervation of Purkinje cells.

V. Gallo, R. Chittajallu. Unwrapping glial cells from the synapse: What lies inside? Science 292, 872-873. [Full Text]

S. H. R. Oliet, R. Piet, D. A. Poulain, Control of glutamate clearance and synaptic efficacy by glial coverage of neurons. Science 292, 923-926. [Abstract] [Full Text]

M. Iino, K. Goto, W. Kakegawa, H. Okado, M. Sudo, S. Ishiuchi, A. Miwa, Y. Takayasu, I. Saito, K. Tsuzuki, S. Ozawa. Glia-synapse interaction through Ca2+-permeable AMPA receptors in Bergmann glia. Science 292, 926-929. [Abstract] [Full Text]