Diffusible Driving and Coupling Signals of the Biological Clock
Abstract
It is well established that the mammalian suprachiasmatic nucleus (SCN) is a biological pacemaker which entrains the activity of organisms to their environment and controls circadian rhythmicity. However, neither the nature of these coupling signal(s) from the SCN, nor their target(s) in the brain are well understood. Fiber efferents from the SCN reach nearby hypothalamic regions, suggesting a coupling role for neural efferent pathways. The SCN produces diffusible signals that reach nearby hypothalamic sites and the cerebrospinal fluid, suggesting a role for a diffusible efferent pathway. We consider the possibility of redundant coupling signals of the SCN, and review evidence suggesting that diffusible elements may-be sufficient to sustain locomotor rhythmicity in adult animals and to restore locomotor rhythmicity in lesioned hamsters bearing SCN grafts. We also provide data for the occurrence of signals., that synchronize oscillators in irrespective of initial phase. The distinct role of neural and diffusible SCN coupling signals, and the role of SCN-driven systems (pineal melatonin rhythms, body temperature) remains to be explored.
Document Details
- Document Type
- Technical Report
- Publication Date
- May 18, 1993
- Accession Number
- ADA267046
Entities
People
- Joseph Lesauter
- Rae Silver
Organizations
- Barnard College