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© The Rockefeller University Press,
0021-9525/2000//1513 $5.00
The Journal of Cell Biology, Volume 149, Number 7,
, 2000 1513-1526
Original Article |
Activity-Dependent Neuronal Control of Gap-Junctional Communication in Astrocytes
christian.giaume{at}college-de-france.fr
A typical feature of astrocytes is their high degree of intercellular communication through gap junction channels. Using different models of astrocyte cultures and astrocyte/neuron cocultures, we have demonstrated that neurons upregulate gap-junctional communication and the expression of connexin 43 (Cx43) in astrocytes. The propagation of intercellular calcium waves triggered in astrocytes by mechanical stimulation was also increased in cocultures. This facilitation depends on the age and number of neurons, indicating that the state of neuronal differentiation and neuron density constitute two crucial factors of this interaction. The effects of neurons on astrocytic communication and Cx43 expression were reversed completely after neurotoxic treatments. Moreover, the neuronal facilitation of glial coupling was suppressed, without change in Cx43 expression, after prolonged pharmacological treatments that prevented spontaneous synaptic activity. Altogether, these results demonstrate that neurons exert multiple and differential controls on astrocytic gap-junctional communication. Since astrocytes have been shown to facilitate synaptic efficacy, our findings suggest that neuronal and astrocytic networks interact actively through mutual setting of their respective modes of communication.
Key Words: neuro–glial interaction • gap junctions • glial cells • connexin 43 • synaptic activity
© 2000 The Rockefeller University Press
Abbreviations used in this paper: [Ca2+]i, intracellular calcium concentration; A/N cocultures, secondary plating of astrocytes on neuron cultures; CNQX, 6-cyano-7-nitroquinoxaline-2,3-dione disodium; Cx, connexin; Cx43, connexin 43; DAPI, 4',6-diamino-2-phenylindol; GABA,
-amino-butyric acid; GFAP, glial fibrillary acid protein; GJC, gap-junctional communication; LY, Lucifer yellow; MAP 2, microtubule-associated protein; N/A cocultures, cocultures of neurons plated on confluent astrocytes; NMDA, N-methyl-D aspartic acid; SSIC, spontaneous synaptic inward currents; TTX, tetrodotoxin.
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