Astrocytes potentiate transmitter release at single hippocampal synapses
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1
CSIC, Instituto Cajal, Spain
We investigated the neuromodulatory role of astrocytes on synaptic physiology at single hippocampal synapses. Using electrophysiological and Ca2+ imaging techniques on rat hippocampal slices, we performed paired recordings from CA1 pyramidal neurons and single astrocytes. Astrocytes were loaded with the Ca2+ indicator Fluo 4 (50 µM) and the Ca2+-cage NP-EGTA (5mM) and were selectively stimulated by UV-flash photolysis (2Hz, 5s). Single synapses of Schaffer collaterals were stimulated at 0.5 Hz.
We found that the selective elevation of Ca2+ in single astrocytes transiently increased the synaptic efficacy due to the potentiation of the probability of transmitter release, without affecting the amplitude of synaptic currents. This form of short-term plasticity was due to SNARE protein- and Ca2+-dependent release of glutamate from astrocytes, that activates presynaptic type I metabotropic glutamate receptors (mGluRs).
The concurrent activity of astrocyte Ca2+ elevation and postsynaptic neuron caused the persistent potentiation of synaptic transmission. Therefore, the temporal coincidence of neuronal and astrocytic signals induced the long-term potentiation (LTP) of hippocampal synaptic transmission.
LTP was independent of NMDA receptor activation and postsynaptic intracellular Ca2+. However, LTP was prevented by blockage of presynaptic type I of mGluRs and synthesis of nitric oxide.
We conclude that astrocytes potentiate synaptic transmission playing an active role in the transfer and storage of synaptic information by the nervous system.
Supported by: MICINN (BFU2007-64764), Cajal Blue Brain and EU (Health-F2-2007-202167)
Keywords:
Astrocytes,
gliotransmitter release,
intracellular ca2+,
neuron-glia communication
Conference:
3rd Mediterranean Conference of Neuroscience , Alexandria, Egypt, 13 Dec - 16 Dec, 2009.
Presentation Type:
Poster Presentation
Citation:
Perea
G and
Araque
A
(2009). Astrocytes potentiate transmitter release at single hippocampal synapses.
Front. Neurosci.
Conference Abstract:
3rd Mediterranean Conference of Neuroscience .
doi: 10.3389/conf.neuro.01.2009.16.163
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Received:
26 Nov 2009;
Published Online:
26 Nov 2009.
*
Correspondence:
Gertrudis Perea, CSIC, Instituto Cajal, Madrid, Spain, gperea@cajal.csic.es