肝臓の昼夜時計の訓練は,食事によって行われる
K A Stokkan1, S Yamazaki, H Tei
1National Science Foundation Center for Biological Timing and Department of Biology, University of Virginia, P.O. Box 400328, Charlottesville, VA 22904-4328, USA. mm7e@virginia.edu
まとめ
制限された食事により,肝臓の遺伝子発現のリズムが,脳のマスタークロック (上性核) から独立して急速に変化した. これは,昼食ヒエラルキーの伝統的な見解に異議を唱え,食事行動が周辺の時計とSCNを結びつける可能性があることを示唆しています.
科学分野:
- クロノバイオロジー クロノバイオロジー
- 分子生物学は分子生物学である.
- 生理学 生理学とは
背景:
- シルカディアンリズムが生物学的プロセスを支配し,光と闇のサイクルが,上下神経核 (SCN) を経由して同期されます.
- 周辺臓器は昼夜間の遺伝子発現リズムを示すが,中央SCNクロックとの協調は不完全である.
- 給食スケジュールのような非光学的なシグナルの影響が,周辺の昼夜組織に及ぼす影響は,調査の重要な分野である.
研究 の 目的:
- 制限された給食スケジュールは,外周組織 (肝臓,肺) と中央SCNにおける昼夜遺伝子発現リズムにどのように影響するか調査する.
- SCNとライトダークサイクルからのシグナルを供給することによって,周辺のクロックエントレインメントの独立性を決定します.
- 哺乳類の昼夜系の階層的組織を再評価する.
主な方法:
- ルシフェラーゼを発現するトランスジェニックのラットモデルを使用して, in vitro で昼夜リズムをモニターしました.
- 肝臓,肺,SCNにおける遺伝子発現リズムを照明・暗闇と制限された栄養状態で比較した.
- 摂食誘導への反応として,周辺および中央の昼間振動器における定量化された相変化.
主要な成果:
- SCNにおける日経リズムが,光と闇のサイクルに同期したままでした.
- 制限食は肝臓の昼夜リズムを急速に引きずり込み,2日以内に約10時間の相変化を引き起こしました.
- 肺のサーカディアンリズムも,食事スケジュールによる大きな影響を示したが,シフトの程度は詳細には示されなかった.
結論:
- 給餌サイクルは,SCNと光暗サイクルに関係なく,肝臓などの周辺の昼夜振動器を独立して誘導することができます.
- これらの発見は,既成の哺乳類の昼夜ヒエラルキーを挑戦し,中央と周辺の時計のより複雑な相互作用を示唆しています.
- 食事を含むリズム的な行動が,周辺の昼間振動器をSCNに結合させる主要なメカニズムとして機能する.
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