Measurement of transcription activity in freely moving mice: Ultradian rhythms and their physiological roles

2017 Fiscal Year Final Research Report

• Project/Area Number: 15K12763
• Research Category: Grant-in-Aid for Challenging Exploratory Research
• Allocation Type: Multi-year Fund
• Research Field: Basic / Social brain science
• Research Institution: Hokkaido University
• Principal Investigator: HONMA Sato 北海道大学, 脳科学研究教育センター, 招へい教員 (20142713)
• Co-Investigator(Kenkyū-buntansha): 織田 善晃 北海道大学, 脳科学研究教育センター, 博士研究員 (20735542)
• Research Collaborator: NAKAMURA Wataru ; ONO Daisuke
• Project Period (FY): 2015-04-01 – 2018-03-31
• Keywords: 生体リズム / 転写調節 / インビボ計測

Outline of Final Research Achievements

In freely moving mice, clock gene expression, continuously recorded by luciferase reporter from the suprachiasmatic nucleus (SCN), exhibits ultradian rhythms in addition to the circadian gene expression rhythm. Since the ultradian periodicities were similar in three clock genes, we hypothesized the common mechanisms generating ultradian rhythms within or near the SCN. In the present study, we aimed to find out the common mechanisms underlying these rhythms.
We found that the ultradian oscillation originated not in the SCN but in the paraventricular nucleus and subparaventricular zone using the co-culture system and calcium imaging. Glutamate and GABA are involved in generating ultradian rhythms. Using an optical fiber system for measuring bioluminescence continuously, we measured Per1-luc and Bmal1-ELuc expression rhythms and found that two rhythms were transiently uncoupled after phase-delaying light pulse. We further confirmed the two rhythms can be separable in culture system.

Free Research Field

環境生理学