| Budget Amount *help |
¥4,800,000 (Direct Cost: ¥4,800,000)
Fiscal Year 1992: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 1991: ¥1,400,000 (Direct Cost: ¥1,400,000)
Fiscal Year 1990: ¥2,600,000 (Direct Cost: ¥2,600,000)
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| Research Abstract |
1. Culture of rat suprachiasmatic nucleus neuron: We have developed a dissociated suprachiasmatic nucleus (SCN) cell culture system in order to begin a cellular analysis of mammalian circadian oscillator. Twenty seven hour oscillation of vasopressin release was observed in SCN cell culture. This finding suggest that cultured SCN neurons retain the capacity for circadian oscillation for a long time, and should provide a useful model to analyze the mammalian clock mechanism.
2. Reentrainment of circadian clock itself to new light-dark cycle: We investigated whether the circadian clock itself reentrain more quickly to a new light-dark cycle than does the overt rhythm of activity.It took 2.4 days and 6.4 days for clock itself and overt activity rhythm to re-entrain to the new light-dark cycle, respectively. This results suggest that the circadian clock itself reentrain very rapidly following change of light-darkcycle, while the overt rhythms of activity take many cycles.
3. Search of proteins related to circadian clock mechanism: We investigated the time-dependent protein in SCN cells harvested every 3 hour from rats kept under constant dark conditions. A 64-kDa protein synthesis rate was rhythmic, and showed two distinct peaks which one of them are observed at around CT 6-9, and the other around CT 21. The peak times consisted with the region of phase-advance induced light and protein synthesis inhibitor.These results indicate the 64kDa protein in SCN may be involved in circadian clock mechanism.
4. We examined the difference of circadian clock mechanism between various species of avian, such as chick, crow, pigeon, owl, sparrow, and quail. The pineal gland of owl did not show the circadian rhythm of melatonin release. On the other hand the other avian, except a quail, showed the circadian oscillation of melatonin release under both LD cycle and DD conditions. These results suggest that circadian clock mechanism of avian pineal is different among the species.
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