Serotonergic integration of circadian clock and ultradian sleep-wake cycles

2014 Fiscal Year Final Research Report

• Project/Area Number: 24621012
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: 睡眠科学
• Research Institution: The Institute of Physical and Chemical Research
• Principal Investigator: MIYAMOTO Hiroyuki 独立行政法人理化学研究所, 脳科学総合研究センター, 研究員 (90312280)
• Project Period (FY): 2012-04-01 – 2015-03-31
• Keywords: サーカディアンリズム / 睡眠・覚醒 / セロトニン / 視交叉上核 / 前脳基底部・視索前野 / 神経活動

Outline of Final Research Achievements

In mammals, the suprachiasmatic nucleus (SCN) of the hypothalamus generates a 24 h rhythm of sleep and arousal. While neuronal spiking activity in the SCN provides a functional circadian oscillator that propagates throughout the brain, the ultradian sleep-wake state is regulated by the basal forebrain/preoptic area (BF/POA). How this SCN circadian oscillation is integrated into the shorter sleep-wake cycles remains unclear. We examined the temporal patterns of neuronal activity in these key brain regions in behaving rats. We identified a diurnal rhythm in the BF/POA that was selectively degraded when diurnal arousal patterns were disrupted by acute brain serotonin depletion despite robust circadian spiking activity in the SCN. Local blockade of serotonergic transmission in the BF/POA was sufficient to disrupt the diurnal sleep-wake rhythm of mice. These results suggest that the serotonergic system enables the BF/POA to couple the SCN circadian signal to ultradian sleep-wake cycles.

Free Research Field

神経科学