Long-lasting changes of calcium oscillations in astrocytes. A new form of glutamate-mediated plasticity.
Long-term changes of synaptic strength in the central nervous system are mediated by an increase of cytosolic calcium concentration ([Ca2+]i) following activation of excitatory neurotransmitter receptors. These phenomena, which represent a possible cellular basis for learning and memory processes in eukaryotes, are believed to be restricted to neurons. Here we provide evidence for a long-term change of the response elicited by the excitatory neurotransmitter glutamate in a non-neuronal cell population of the central nervous system, i.e. visual cortical astrocytes in culture. Stimulation with glutamate induces in astrocytes a regular pattern of [Ca2+]i oscillations. A second stimulation, after an interval ranging from 2 to 60 min, induces an oscillatory response characterized by an increased frequency. Induction of this change in the astrocyte response is abolished by a specific inhibitor of the nitric oxide synthase and recovers upon exogenous nitric oxide generation or addition of a permeant cGMP analogue. Local brief pulses of glutamate to individual astrocytes, at a rate of 1 Hz, also elicit [Ca2+]i oscillations whose frequency increases following a second series of pulses. The long-lasting modification in the [Ca2+]i oscillatory response induced by glutamate in astrocytes demonstrates that in the central nervous system cellular memory is not a unique feature of neurons.
Pasti
L
L
Department of Biomedical Sciences, University of Padova, Italy.
Pozzan
T
T
Carmignoto
G
G
D018750:6-Cyano-7-nitroquinoxaline-2,3-dione / Q000494:pharmacology; D000818:Animals; D000831:Animals, Newborn; D001120:Arginine / Q000031:analogs & derivatives / Q000494:pharmacology; D001253:Astrocytes / Q000187:drug effects / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism*; D002478:Cells, Cultured; D018698:Glutamic Acid / Q000494:pharmacology*; D007700:Kinetics; D019331:NG-Nitroarginine Methyl Ester; D009569:Nitric Oxide / Q000037:antagonists & inhibitors; D009991:Oscillometry; D051381:Rats; D017208:Rats, Wistar; D013237:Stereoisomerism; D013997:Time Factors; D014793:Visual Cortex / Q000378:metabolism*
D009569:Nitric Oxide; D018698:Glutamic Acid; D018750:6-Cyano-7-nitroquinoxaline-2,3-dione; D001120:Arginine; D002118:Calcium; D019331:NG-Nitroarginine Methyl Ester