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The suprachiasmatic nucleus: a clock of multiple components
Han S Lee1, Heather J Billings, Michael N Lehman
1Department of Cell Biology, Neurobiology and Anatomy, Neuroscience Program, University of Cincinnati College of Medicine, Cincinnati, OH 45267-0521, USA.
Journal of Biological Rhythms
|December 12, 2003
Summary
The suprachiasmatic nucleus (SCN) has distinct rhythmic and nonrhythmic cell populations. Light-responsive cells are mainly in the nonrhythmic core, influencing SCN pacemaker function.
Area of Science:
- Neuroscience
- Chronobiology
Background:
- The suprachiasmatic nucleus (SCN) is the master circadian pacemaker.
- Understanding SCN cellular heterogeneity is crucial for deciphering tissue-level pacemaker function.
Purpose of the Study:
- To investigate cellular and regional heterogeneity within the SCN.
- To identify which SCN cells are endogenously rhythmic and/or directly light-responsive.
Main Methods:
- Analysis of endogenous rhythms in electrical activity, gene/protein expression, and protein phosphorylation.
- Mapping of rhythmic and light-responsive cell distributions within the SCN.
Main Results:
- The SCN comprises distinct rhythmic and nonrhythmic cellular components.
- Rhythmic neurons are primarily in rostral and dorsomedial SCN, forming a "shell" at mid-caudal levels.
- Nonrhythmic cells form a central "core," largely overlapping with light-responsive cells.
Conclusions:
- SCN organization features a complementary "shell" of rhythmic cells and a "core" of nonrhythmic, light-responsive cells.
- Species-specific variations exist in SCN component boundaries and neurochemical phenotypes.
- Intercellular communication between SCN components is vital for its pacemaker properties.