| Project/Area Number |
05454142
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
Environmental physiology (including Physical medicine and Nutritional physiology)
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| Research Institution | Hokkaido University |
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Principal Investigator |
HONMA Kenichi Hokkaido Uni.Sch.of Med., Professor, 医学部, 教授 (40113625)
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| Co-Investigator(Kenkyū-buntansha) |
KATSUNO Yumiko Hokkaido Univ.Sch.of Med., Instructor, 医学部, 助手 (80177419)
HONMA Sato Hokkaido Uni.Sch.of Med., Associate Professor, 医学部, 助教授 (20142713)
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| Project Period (FY) |
1993 – 1994
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| Project Status |
Completed (Fiscal Year 1994)
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| Budget Amount *help |
¥6,800,000 (Direct Cost: ¥6,800,000)
Fiscal Year 1994: ¥1,200,000 (Direct Cost: ¥1,200,000)
Fiscal Year 1993: ¥5,600,000 (Direct Cost: ¥5,600,000)
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| Keywords | Humans / Circadian rhythm / Sleep and wake / Melatonin / Social entrainment / Light / Dopamine / Phase response / Circadian Rhythm / Social Entrainment / Melatonin / Rectal Temperature / Light / Methamphetamine / Sleep EEG / Animal Model |
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| Research Abstract |
1) Characteristics of the human circadian system
1. Coupling strength of circadian rhythms : Internal desynchronization of free-running circadian rhythms was observed in all subjects under dim light conditions between sleep-wake and plasma melatonin rhythms. Sleep structure was also changed, which was characterized by altered REM sleep propensity. Light might increase the strength of oscillatory coupling.
2. Social entrainment of circadian melatonin rhythm : Forced sleep-wake schedule of a 24-hour period entrained the free-runing circadian rhythm of plasma melatonin in 3 out of 8 subjects under light intensity of 200 1x. While, the forced schedule failed to entrain the melatonin rhythm under light intensity of 5 1x. The forced sleep-wake schedule does not seem to have an entraining capability, and the social entrainment observed under 200 1x is likely due to an associated light-dark cycle. On the other hand, bright light was demonstrated to facilitate re-entrainment of circadian melatonin rhythm.
2) Oscillatory mechanism of sleep-wake rhythm in model animals.
1. Internal desynchronization by methamphetamine : Chronic administration of methamphetamine in rats produced internal desynchronization in locomotor activity rhythm, which was quite similar to that observed in the human circadian system. The sleep structure was also changed by methamphetamine.
2. Social entrainment and the dopaminergic mechanism : Methamphetamine-induced locomotor rhythm was entrained by feeding schedule, which was explained at least theoretically by a phase response curve for a single injection with haloperidol, a dopaminergic antagonist. The central dopaminergic mechanism was suggested to be involved in social entrainment of sleep-wake rhythm.
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