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Accession number;04A0442619
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| Title;Regulation by astrocytic ATP of synaptic transmission |
| Author;
KOIZUMI SHUICHI
(National Inst. Health Sciences, JPN)
INOUE KAZUHIDE
(National Inst. Health Sciences, JPN)
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Journal Title;Folia Pharmacologica Japonica
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Journal Code:G0740A
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ISSN:0015-5691
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VOL.123;NO.6;PAGE.389-396,412(2004)
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| Figure&Table&Reference;FIG.4, REF.31 |
| Pub. Country;Japan |
| Language;Japanese |
| Abstract;Originally ascribed to having only passive roles in the CNS, astrocytes are now known to have an active role in the regulation of synaptic transmission. Neuronal activity can evoke Ca2+ transients in astrocytes and Ca2+ transients in astrocytes can evoke changes in neuronal activity. The excitatory neurotransmitter glutamate has been shown to mediate such bi-directional communication between astrocytes and neurons. We demonstrate here that ATP, a primary mediator of intercellular Ca2+ signaling among astrocytes, also mediates intercellular signaling between astrocytes and neurons in hippocampal cultures. Mechanical stimulation of astrocytes evoked Ca2+ waves mediated by the release of ATP and activation of P2 receptors. Mechanically evoked Ca2+ waves led to decreased excitatory glutamatergic synaptic transmission in an ATP-dependent manner. Exogenous application of ATP does not affect post-synaptic glutamatergic responses but decreased pre-synaptic exocytotic events. Finally, we show that astrocytes exhibit spontaneous Ca2+ oscillations mediated by extracellular ATP and that inhibition of these Ca2+ responses enhanced excitatory glutamatergic transmission. We therefore conclude that ATP released from astrocytes exerts tonic and activity-dependent down-regulation of synaptic transmission via pre-synaptic mechanisms. (author abst.) |
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