Circadian rhythms of extracellular ATP accumulation in suprachiasmatic nucleus cells and cultured astrocytes
- 28 August 2009
- journal article
- Published by Wiley in European Journal of Neuroscience
- Vol. 30 (5), 869-876
- https://doi.org/10.1111/j.1460-9568.2009.06874.x
Abstract
The master circadian pacemaker located within the suprachiasmatic nucleus (SCN) of the mammalian brain controls system‐level rhythms in animal physiology. Specific SCN outputs synchronize circadian physiological rhythms in other brain regions. Within the SCN, communication among neural cells provides for the coordination of autonomous cellular oscillations into ensemble rhythms. ATP is a neural transmitter involved in local communication among astrocytes and between astrocytes and neurons. Using a luciferin–luciferase chemiluminescence assay, we have demonstrated that ATP levels fluctuate rhythmically within both SCN2.2 cell cultures and the rat SCN in vivo. SCN2.2 cells generated circadian oscillations in both the production and extracellular accumulation of ATP. Circadian fluctuations in ATP accumulation persisted with an average period (τ) of 23.7 h in untreated as well as vehicle‐treated and forskolin‐treated SCN2.2 cells, indicating that treatment with an inductive stimulus is not necessary to propagate these rhythms. ATP levels in the rat SCN in vivo were marked by rhythmic variation during exposure to 12 h of light and 12 h of dark or constant darkness, with peak accumulation occurring during the latter half of the dark phase or subjective night. Primary cultures of cortical astrocytes similarly expressed circadian oscillations in extracellular ATP accumulation that persisted for multiple cycles with periods of about 23 h. These results suggest that circadian oscillations in extracellular ATP levels represent a physiological output of the mammalian cellular clock, common to the SCN pacemaker and astrocytes from at least some brain regions, and thus may provide a mechanism for clock control of gliotransmission between astrocytes and to neurons.Keywords
This publication has 36 references indexed in Scilit:
- Challenging the omnipotence of the suprachiasmatic timekeeper: are circadian oscillators present throughout the mammalian brain?European Journal of Neuroscience, 2007
- Astrocytes Coordinate Synaptic Networks: Balanced Excitation and InhibitionPhysiology, 2006
- Circadian rhythms from multiple oscillators: lessons from diverse organismsNature Reviews Genetics, 2005
- Astrocytes generate Na + -mediated metabolic wavesProceedings of the National Academy of Sciences of the United States of America, 2004
- Clock Genes, Oscillators, and Cellular Networks in the Suprachiasmatic NucleiJournal of Biological Rhythms, 2004
- Olfactory bulb neurons express functional, entrainable circadian rhythmsEuropean Journal of Neuroscience, 2004
- Effects of altered Clock gene expression on the pacemaker properties of SCN2.2 cells and oscillatory properties of NIH/3T3 cellsNeuroscience, 2004
- Oscillating on Borrowed Time: Diffusible Signals from Immortalized Suprachiasmatic Nucleus Cells Regulate Circadian Rhythmicity in Cultured FibroblastsJournal of Neuroscience, 2001
- Immortal Time: Circadian Clock Properties of Rat Suprachiasmatic Cell LinesScience, 1999
- Adenosine modulation of calcium currents and presynaptic inhibition of GABA release in suprachiasmatic and arcuate nucleus neurons.Journal of Neurophysiology, 1997