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Circadian modulation of calcium levels in cells in the suprachiasmatic nucleus

Circadian modulation of calcium levels in cells in the suprachiasmatic nucleus There is reason to believe that resting free calcium concentration (Ca2+)i in neurons in the suprachiasmatic nucleus (SCN) may vary with the circadian cycle. In order to start to examine this hypothesis, optical techniques were utilized to estimate resting Ca2+ levels in SCN cells in a rat brain slice preparation. (Ca2+)i measured from the soma was significantly higher in the day than in the night. Animals from a reversed light–dark cycle were used to confirm that the phase of the rhythm was determined by the prior light–dark cycle. The rhythm in Ca2+ levels continued to be expressed in tissue collected from animals maintained in constant darkness, thus confirming the endogenous nature of this variation. Interestingly, the rhythm in Ca2+ levels was not observed when animals were housed in constant light. Finally, the rhythm in Ca2+ levels was prevented when slices were exposed to tetrodotoxin (TTX), a blocker of voltage‐sensitive sodium channels. Similar results were obtained with the voltage‐sensitive Ca2+ channel blocker methoxyverapamil. These observations suggest a critical role for membrane events in driving the observed rhythm in Ca2+. Conceptually, this rhythm can be thought of as an output of the circadian oscillator. Because (Ca2+)i is known to play a critical role in many cellular processes, the presence of this rhythm is likely to have many implications for the cell biology of SCN neurons. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png European Journal of Neuroscience Wiley

Circadian modulation of calcium levels in cells in the suprachiasmatic nucleus

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References (49)

Publisher
Wiley
Copyright
Copyright © 2000 Wiley Subscription Services, Inc., A Wiley Company
ISSN
0953-816X
eISSN
1460-9568
DOI
10.1046/j.1460-9568.2000.00939.x
Publisher site
See Article on Publisher Site

Abstract

There is reason to believe that resting free calcium concentration (Ca2+)i in neurons in the suprachiasmatic nucleus (SCN) may vary with the circadian cycle. In order to start to examine this hypothesis, optical techniques were utilized to estimate resting Ca2+ levels in SCN cells in a rat brain slice preparation. (Ca2+)i measured from the soma was significantly higher in the day than in the night. Animals from a reversed light–dark cycle were used to confirm that the phase of the rhythm was determined by the prior light–dark cycle. The rhythm in Ca2+ levels continued to be expressed in tissue collected from animals maintained in constant darkness, thus confirming the endogenous nature of this variation. Interestingly, the rhythm in Ca2+ levels was not observed when animals were housed in constant light. Finally, the rhythm in Ca2+ levels was prevented when slices were exposed to tetrodotoxin (TTX), a blocker of voltage‐sensitive sodium channels. Similar results were obtained with the voltage‐sensitive Ca2+ channel blocker methoxyverapamil. These observations suggest a critical role for membrane events in driving the observed rhythm in Ca2+. Conceptually, this rhythm can be thought of as an output of the circadian oscillator. Because (Ca2+)i is known to play a critical role in many cellular processes, the presence of this rhythm is likely to have many implications for the cell biology of SCN neurons.

Journal

European Journal of Neuroscience – Wiley

Published: Feb 1, 2000

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