Challenging the omnipotence of the suprachiasmatic timekeeper: are circadian oscillators present throughout the mammalian brain?
- 6 June 2007
- journal article
- review article
- Published by Wiley in European Journal of Neuroscience
- Vol. 25 (11), 3195-3216
- https://doi.org/10.1111/j.1460-9568.2007.05581.x
Abstract
The suprachiasmatic nucleus of the hypothalamus (SCN) is the master circadian pacemaker or clock in the mammalian brain. Canonical theory holds that the output from this single, dominant clock is responsible for driving most daily rhythms in physiology and behaviour. However, important recent findings challenge this uniclock model and reveal clock‐like activities in many neural and non‐neural tissues. Thus, in addition to the SCN, a number of areas of the mammalian brain including the olfactory bulb, amygdala, lateral habenula and a variety of nuclei in the hypothalamus, express circadian rhythms in core clock gene expression, hormone output and electrical activity. This review examines the evidence for extra‐SCN circadian oscillators in the mammalian brain and highlights some of the essential properties and key differences between brain oscillators. The demonstration of neural pacemakers outside the SCN has wide‐ranging implications for models of the circadian system at a whole‐organism level.Keywords
This publication has 102 references indexed in Scilit:
- Expression of prokineticins and their receptors in the adult mouse brainJournal of Comparative Neurology, 2006
- A Clock Shock: Mouse CLOCK Is Not Required for Circadian Oscillator FunctionNeuron, 2006
- Circadian Gene Expression in Individual FibroblastsCell, 2004
- The mammalian retina as a clockCell and tissue research, 2002
- Output pathways of the mammalian suprachiasmatic nucleus: coding circadian time by transmitter selection and specific targetingCell and tissue research, 2002
- Suprachiasmatic nucleus organizationCell and tissue research, 2002
- Antiphase Circadian Expression betweenBMAL1andperiodHomologue mRNA in the Suprachiasmatic Nucleus and Peripheral Tissues of RatsBiochemical and Biophysical Research Communications, 1998
- GABA is the principal neurotransmitter of the circadian systemNeuroscience Letters, 1993
- Immunocytochemical localization of calretinin in the forebrain of the ratJournal of Comparative Neurology, 1991
- Effects of T cycles of light/darkness and periodic forced activity on methamphetamine-induced rhythms in intact and SCN-lesioned rats: Explanation by an hourglass-clock modelPhysiology & Behavior, 1990