Biology Reference
In-Depth Information
CHAPTER FOUR
Peripheral Circadian Oscillators:
Time and Food
Ruud Buij s * , Roberto Salgado , Elizabeth Sabath * , Carolina Escobar {
* Departamento de Biolog´a Celular y Fisiolog´a, Instituto de Investigaciones Biom´dicas, Universidad Nacional
Aut ´ noma de M ´ xico, Distrito Federal, Mexico
Departamento de Biolog´a Celular, Facultad de Ciencias, Universidad Aut´noma de San Luis Potos´,
San Luis Potos´, Mexico
{ Departamento de Anatom´a, Facultad de Medicina, Universidad Nacional Aut´noma de M´xico,
Distrito Federal, Mexico
Contents
1.
Introduction
84
2. The SCN as Master Clock
85
3. The Peripheral Oscillators and Their Relationship with Clock Genes
86
4. The SCN as the Driving Force Behind the Oscillators
87
5. Synchronization of the Circadian System by the SCN
89
6. Timing by Food?
90
7. Energy Oscillation in the Cell
92
7.1 The NAD/SIRT1 clock gene link
92
7.2 Metabolism, AMPK, and clock genes
92
8. Heme as Another Metabolic Clock Connection Possibility
94
9. The Link Between Clock Genes and Metabolic Genes
95
10. Conclusions
98
Acknowledgments
99
References
99
Abstract
The suprachiasmatic nucleus (SCN) provides timing to the brain and to the whole
organism. Its rhythmic signal to mainly hypothalamic structures results in a synchro-
nized hormonal and autonomic output to the body that coordinates behavior and
physiology. As a result of this, the expression of clock genes in all organs has a rhythm
that is dictated by the SCN. Together with these clock genes, a number of cellular pro-
cesses follow a similar rhythm, whereby it has been proposed that these events are
driven at least, in part, by clock genes.
Together, this forms a multiple oscillating system that interacts and under normal
conditions is synchronized by the SCN. The autonomic and hormonal outputs from the
SCN are examples of messages that are clearly targeted; the behaviors driven by the SCN
are examples of messages that may have more diffuse targets. For example, food intake
 
 
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