Basal levels of adenosine modulate mGluR5 on rat hippocampal astrocytes.
Neuronal activity elicits increases in intracellular Ca2+ in astrocytes, which in turn can elevate neuronal Ca2+ and potentiate the efficacy of excitatory synaptic transmission. Therefore, understanding the modulation of astrocyte Ca2+ elevations by neurotransmitters should aid in understanding astrocyte-neuronal interactions. On cultured hippocampal microislands containing only astrocytes, activation of metabotropic glutamate receptors (mGluRs) with the specific agonist 1S,3R-ACPD triggers Ca2+ elevations that are potentiated by adenosine A1 receptor activation. A1 receptor modulation of mGluR-induced Ca2+ elevations is blocked by pertussis toxin and is mimicked by the wasp venom peptide mastoparan, suggesting that potentiation occurs by means of a G(i/o) mechanism. Surprisingly, on microislands containing only astrocytes, A1 receptor antagonism or adenosine degradation suppresses mGluR-triggered Ca2+ elevations, strongly suggesting that astrocytes are a source of physiologically relevant concentrations of adenosine.
Cormier
R J
RJ
Department of Psychiatry, Washington University School of Medicine, St. Louis, Missouri 63110, USA.
Mennerick
S
S
Melbostad
H
H
Zorumski
C F
CF
D000241:Adenosine / Q000378:metabolism*; D000818:Animals; D000831:Animals, Newborn; D001253:Astrocytes / Q000187:drug effects* / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism; D002478:Cells, Cultured / Q000187:drug effects / Q000378:metabolism; D019204:GTP-Binding Proteins / Q000187:drug effects / Q000378:metabolism; D006624:Hippocampus / Q000187:drug effects* / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D043705:Receptor, Adenosine A2A; D064529:Receptor, Metabotropic Glutamate 5; D018094:Receptors, Metabotropic Glutamate / Q000187:drug effects / Q000378:metabolism*; D018047:Receptors, Purinergic P1 / Q000378:metabolism
C578937:Grm5 protein, rat; D043705:Receptor, Adenosine A2A; D064529:Receptor, Metabotropic Glutamate 5; D018094:Receptors, Metabotropic Glutamate; D018047:Receptors, Purinergic P1; D019204:GTP-Binding Proteins; D000241:Adenosine; D002118:Calcium