1997 Fiscal Year Final Research Report Summary
Mechanisms of circadian rhythm analyzed from transcription factor of mRNA in suprachiasmatic nucleus
| Project/Area Number |
08670086
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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.Junior Assistant Professor, 医学部, 助手 (70094357)
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| Co-Investigator(Kenkyū-buntansha) |
FUJIMOTO Ichirou Okazaki Natl.Inst.Physiol Lab.Neuronal Inf.Research Associate, 神経情報, 助手 (70264710)
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| Project Period (FY) |
1996 – 1997
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| Keywords | Suprachiasmatic nuclei / Arg-vasopressin / transcription / GABA / c-fos / AP-1 / RT-PCR / プロモーター |
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| Research Abstract |
Mammalian circadian rhythm is regulated by a pacemaker in the suprachiasmatic nuclei (SCN) of hypothalamus. The SCN containing variety of peptides. Argvasopressin (AVP) containing neuron is one of the output neuron of circadian signal from the SCN to the other brain area. For the entraining mechanism of pacemaker, vasoactive intestinal peptide (VIP), gastrin-releasing peptide are considered to be concerned. While the function of these peptides on the AVP release is reciprocal ; i.e.we found that the VIP increased AVP release, while gastrin-releasing peptide decreased AVP release. Many SCN-specific mRNA from are found by using differential display PCR throughout a day. However, a few products appeared only at CT 20-23. AVP peptide in SCN is higher in subjective day than in night. The qualitative assay of AVPmRNA in SCN is desired to be analyzed in individual animals to compare the peptide levels and other circadian index. We could detect the AVPmRNA levels extracted from two punches of SCN in one rat by using RT-PCR with specific primers. The pattern of day-night variations in PCR product-intensity are similar with that analyzed by Northern blot. These day-night variations were free-run until 21st day under the constant dim light. We find the differential responses in SCN (parvocellular AVP containing neuron) and supraoptic nucleus (magunocellular) against to GABA and corticosterone/dexamethasone. Photic atimulation from retina induces c-fos development in SCN.c-fos development couples with the phase responses and other indexes of circadian rhythm. 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 AVPmRNA originating from the SCN.
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