Gap junctions couple astrocytes but not neurons in dissociated cultures of rat suprachiasmatic nucleus

Individual neurons dissociated from rat suprachiasmatic nucleus can express independently phased circadian firing rhythms in culture. The phases of these rhythms are unperturbed by reversible blockade of neuronal firing lasting 2.5 days, indicating that multiple circadian clocks continue to operate...

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Bibliographic Details
Published in:Brain research 1996-01, Vol.706 (1), p.30-36
Main Authors: Welsh, David K., Reppert, Steven M.
Format: Article
Language:English
Subjects:
Animals
Astrocyte
Astrocytes - cytology
Biological and medical sciences
Biotin - analogs & derivatives
Cell Communication
Cell culture
Cells, Cultured
Circadian rhythm
Circadian Rhythm - physiology
Fundamental and applied biological sciences. Psychology
Gap junction
Gap Junctions - physiology
Isolated neuron and nerve. Neuroglia
Neuron
Neurons - cytology
Rats
Rats, Sprague-Dawley
Suprachiasmatic nucleus
Suprachiasmatic Nucleus - cytology
Suprachiasmatic Nucleus - physiology
Vertebrates: nervous system and sense organs
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Summary:Individual neurons dissociated from rat suprachiasmatic nucleus can express independently phased circadian firing rhythms in culture. The phases of these rhythms are unperturbed by reversible blockade of neuronal firing lasting 2.5 days, indicating that multiple circadian clocks continue to operate in the absence of conventional synaptic transmission. The possibility remains, however, that these circadian rhythms might depend on some other form of intercellular communication. In the present study, a potential role for gap junctional coupling in SCN cultures was evaluated by introduction of the tracer molecule Neurobiotin into both neurons ( n = 98) and astrocytes ( n = 10), as well as by immunolabeling for specific connexins, the molecular components of gap junctions. Astrocytes were extensively coupled to each other by connexin43-positive gap junctions, but no evidence was found for coupling of neurons to each other or to astrocytes. These data support the hypothesis that neurons expressing independently phased circadian rhythms in SCN cultures (‘clock cells’) are autonomous, single cell circadian oscillators, but do not exclude a role for glia in synchronizing neuronal clock cells in vivo.
ISSN:0006-8993
1872-6240
DOI:10.1016/0006-8993(95)01172-2