1999 Fiscal Year Final Research Report Summary
Mechanisms of circadian rhythm analyzed from transcription factor of mRNA in suprachiasmatic nucleus
| Project/Area Number |
10670069
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Environmental physiology (including Physical medicine and Nutritional physiology)
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| Research Institution | Nagoya City University |
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Principal Investigator |
ISOBE Yoshiaki Nagoya City University, Med. Sch. Assistant Professor, 医学部, 助手 (70094357)
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| Project Period (FY) |
1998 – 1999
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| Keywords | Suprachiasmatic nuclei / Arg-vasopressin / transcription / mRNA / c-fos / AP-1 / RT-PCR |
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| Research Abstract |
Arg-vasopressin (AVP) containing neurons in the suprachiasmatic nucleus (SCN) is one of the output paths of circadian information to other parts of the brain. The AVP contents show a free-running rhythm under the constant dim light, whose acrophase is developing during the early period of subjective day. It is useful to compare the AVP peptide levels with its coding mRNA in individual animals. In the present study, we analyzed the AVP mRNA levels by reverse transcription PCR (PT-PCR). We could detect the AVP mRNA levels extracted from two punches of SCN in one rat by using PT-PCR with specific primers. Effects of light or dark response to the SCN AVP mRNA were examined. The light responses to AVP peptide were more effective than to the dark. While, the AVP mRNA did not show an obvious change after transition to new lighting regime. The patterns of day-night variations in PCR product-intensity are similar with that analyzed by Northern blot. These day-night variations free-run until 21st day under the constant dim light. We find the differential responses in SCN (parvocellular AVP containing neuron) and supraoptic nucleus (magnocellular) against to GABA and corticosterone/dexamethasone. Photic stimulation from retina induces c-fos development in SCN. C-fos development couples with the phase responses and other indexes of circadian rhythm. These results suggest that the AVP peptide rhythm be checked not only by the control of synthesis, but also by the other systems. It is reasonable to speculate that the AVP coding gene might containing IEG(c-fos) binding site at the upstream of 5' promoter area. Although, the AVP coding DNA has no AP-1 binding site that was sequenced from the genome obtained from supraoptic nucleus or other brain area. We are searching the specific genome, which code AVP mRNA originating from the SCN.
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