TY - JOUR
T1 - P2X7 receptors mediate ATP release and amplification of astrocytic intercellular Ca2+ signaling
AU - Suadicani, Sylvia O.
AU - Brosnan, Celia F.
AU - Scemes, Eliana
PY - 2006/2/1
Y1 - 2006/2/1
N2 - Modulation of synaptic transmission and brain microcirculation are new roles ascribed to astrocytes in CNS function. A mechanism by which astrocytes modify neuronal activity in the healthy brain depends on fluctuations of cytosolic Ca2+ levels, which regulate the release of "gliotransmitters" via an exocytic pathway. Under pathological conditions, however, the participation of other pathways, including connexin hemichannels and the pore-forming P2X7R, have been proposed but remain controversial. Through the use of genetically modified 1321N1 human astrocytoma cells and of spinal cord astrocytes derived from neonatal Cx43- and P2X7R-null mice, we provide strong evidence that P2X7Rs, but not Cx43 hemichannels, are sites of ATP release that promote the amplification of Ca2+ signal transmission within the astrocytic network after exposure to low divalent cation solution. Moreover, our results showing that gap junction channel blockers (heptanol, octanol, carbenoxolone, flufenamic acid, and mefloquine) are antagonists of the P2X7R indicate the inadequacy of using these compounds as evidence for the participation of connexin hemichannels as sites of gliotransmitter release.
AB - Modulation of synaptic transmission and brain microcirculation are new roles ascribed to astrocytes in CNS function. A mechanism by which astrocytes modify neuronal activity in the healthy brain depends on fluctuations of cytosolic Ca2+ levels, which regulate the release of "gliotransmitters" via an exocytic pathway. Under pathological conditions, however, the participation of other pathways, including connexin hemichannels and the pore-forming P2X7R, have been proposed but remain controversial. Through the use of genetically modified 1321N1 human astrocytoma cells and of spinal cord astrocytes derived from neonatal Cx43- and P2X7R-null mice, we provide strong evidence that P2X7Rs, but not Cx43 hemichannels, are sites of ATP release that promote the amplification of Ca2+ signal transmission within the astrocytic network after exposure to low divalent cation solution. Moreover, our results showing that gap junction channel blockers (heptanol, octanol, carbenoxolone, flufenamic acid, and mefloquine) are antagonists of the P2X7R indicate the inadequacy of using these compounds as evidence for the participation of connexin hemichannels as sites of gliotransmitter release.
KW - ATP release
KW - Astrocyte
KW - Ca waves
KW - Connexin hemichannels
KW - Gap junction blockers
KW - Glia
UR - http://www.scopus.com/inward/record.url?scp=32544448639&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=32544448639&partnerID=8YFLogxK
U2 - 10.1523/JNEUROSCI.3902-05.2006
DO - 10.1523/JNEUROSCI.3902-05.2006
M3 - Article
C2 - 16452661
AN - SCOPUS:32544448639
SN - 0270-6474
VL - 26
SP - 1378
EP - 1385
JO - Journal of Neuroscience
JF - Journal of Neuroscience
IS - 5
ER -