スイミン ト セイタイ リズム
Sleep and Biological Clock
Sei, Hiroyoshi Department of Integrative Physiology, Institute of Health Biosciences, The University of Tokushima Graduate School Tokushima University Educator and Researcher Directory KAKEN Search Researchers
Circadian rhythm is an endogenous rhythm controlled by a master oscillator (biological clock) in the supra-chiasmatic nucleus (SCN), affecting on the almost all physiological functions including sleep/wake regulation. Recently the biological clock has been shown to function at the molecular level, and several circadian-related genes have been identified, such as the Clock, Per 1-3, Bmal 1 or Cry 1, 2.
We observed the sleep/wake rhythm in cry 1, 2 double knockout mice and clock mutant mice. Both strains have lost the circadian oscillation in the expression of circadian-related genes. Cry 1, 2 double knockout mice show the entrained sleep/wake rhythm to ordinary light-dark (LD) cycle, although they show completely flattened rhythm under the constant dark (DD) condition. On the other hand, clock mutant mice show the persistent circadian sleep/wake rhythm under even DD conditions. Although the expression of circadian-related genes do not oscillate, the clock mutant mice have potent circadian rhythm in body core temperature, behavior, sleep/wake and cortisol etc. The clock mutant mice have a longer (27 hrs) period of free-running rhythm under DD condition, and the phase of sleep/wake rhythm is delayed for about two hours comparing to the wild-type under LD condition.
The important role of the circadian-related genes in the sleep/wake regulation has been indicated. The functional impairment of the circadian-related genes may be involved in the sleep disorders, such as insomnia or hypersomnia.
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