Abstract
The circadian system in mammals consists of the central clock in the hypothalamic suprachiasmatic nucleus (SCN) and the peripheral clocks in a variety of tissues and organs. The SCN clock entrains to a light-dark cycle and resets the peripheral clocks. In addition, there are at least two other clocks in the circadian domain which are independent of the SCN and which entrain to nonphotic time cues: methamphetamine (MAP)-induced and restricted daily feeding (RF)-induced clocks. Neither the site nor the mechanism of SCN-independent clocks is known. Canonical clock genes for circadian oscillation are not required for the expression of either SCN-independent rhythm. The central catecholaminergic system is probably involved in the expression of the SCN-independent rhythms, especially of the MAP-induced rhythm. MAP-induced activity rhythms in rats and the sleep-wake cycles in humans share unique phenomena such as spontaneous internal desynchronization, circabidian rhythm and nonphotic entrainment, suggesting overlapping oscillatory mechanisms. The SCN-independent clock is an adaptation that regulates behavior in response to nonphotic time cues, and seems to be closely related to the arousal mechanism.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.