title: Immunogold detection of L-glutamate and D-serine in small synaptic-like microvesicles in adult hippocampal astrocytes.
abstract: Glutamate and the N-methyl-D-aspartate receptor ligand D-serine are putative gliotransmitters. Here, we show by immunogold cytochemistry of the adult hippocampus that glutamate and D-serine accumulate in synaptic-like microvesicles (SLMVs) in the perisynaptic processes of astrocytes. The estimated concentration of fixed glutamate in the astrocytic SLMVs is comparable to that in synaptic vesicles of excitatory nerve terminals (≈ 45 and ≈ 55 mM, respectively), whereas the D-serine level is about 6 mM. The vesicles are organized in small spaced clusters located near the astrocytic plasma membrane. Endoplasmic reticulum is regularly found in close vicinity to SLMVs, suggesting that astrocytes contain functional nanodomains, where a local Ca(2+) increase can trigger release of glutamate and/or D-serine.
authors.affiliation: Department of Anatomy, Centre for Molecular Biology and Neuroscience, Institute of Basic Medical Sciences, University of Oslo, 0317 Oslo, Norway.
authors.forename: L H
authors.initials: LH
authors.lastname: Bergersen
authors.forename: C
authors.initials: C
authors.lastname: Morland
authors.forename: L
authors.initials: L
authors.lastname: Ormel
authors.forename: J E
authors.initials: JE
authors.lastname: Rinholm
authors.forename: M
authors.initials: M
authors.lastname: Larsson
authors.forename: J F H
authors.initials: JF
authors.lastname: Wold
authors.forename: A T
authors.initials: AT
authors.lastname: Røe
authors.forename: A
authors.initials: A
authors.lastname: Stranna
authors.forename: M
authors.initials: M
authors.lastname: Santello
authors.forename: D
authors.initials: D
authors.lastname: Bouvier
authors.forename: O P
authors.initials: OP
authors.lastname: Ottersen
authors.forename: A
authors.initials: A
authors.lastname: Volterra
authors.forename: V
authors.initials: V
authors.lastname: Gundersen
mesh_terms: D000818:Animals; D001253:Astrocytes / Q000378:metabolism*; D002478:Cells, Cultured; D018698:Glutamic Acid / Q000378:metabolism*; D006046:Gold; D006624:Hippocampus / Q000378:metabolism*; D007150:Immunohistochemistry / Q000379:methods*; D051381:Rats; D017208:Rats, Wistar; D012694:Serine / Q000378:metabolism*; D013572:Synaptic Vesicles / Q000378:metabolism*
chemical_list: D018698:Glutamic Acid; D012694:Serine; D006046:Gold