PT  - JOURNAL ARTICLE
AU  - Jamie M. Zeitzer
AU  - Christine L. Buckmaster
AU  - Karen J. Parker
AU  - Craig M. Hauck
AU  - David M. Lyons
AU  - Emmanuel Mignot
TI  - Circadian and Homeostatic Regulation of Hypocretin in a Primate Model: Implications for the Consolidation of Wakefulness
AID  - 10.1523/JNEUROSCI.23-08-03555.2003
DP  - 2003 Apr 15
TA  - The Journal of Neuroscience
PG  - 3555--3560
VI  - 23
IP  - 8
4099  - http://www.jneurosci.org/content/23/8/3555.short
4100  - http://www.jneurosci.org/content/23/8/3555.full
SO  - J. Neurosci.2003 Apr 15; 23
AB  - In humans, consolidation of wakefulness into a single episode can be modeled as the interaction of two processes, a homeostatic “hour-glass” wake signal that declines throughout the daytime and a circadian wake-promoting signal that peaks in the evening. Hypocretins, novel hypothalamic neuropeptides that are dysfunctional in the sleep disorder narcolepsy, may be involved in the expression of the circadian wake-promoting signal. Hypocretins (orexins) are wake-promoting peptides, but their role in normal human sleep physiology has yet to be determined. We examined the daily temporal pattern of hypocretin-1 in the cisternal CSF of the squirrel monkey, a New World primate with a pattern of wake similar to that of humans. Hypocretin-1 levels peaked in the latter third of the day, consistent with the premise that hypocretin-1 is involved in wake regulation. When we lengthened the wake period by 4 hr, hypocretin-1 concentrations remained elevated, indicating a circadian-independent component to hypocretin-1 regulation. Changes in the stress hormone cortisol were not correlated with hypocretin-1 changes. Although hypocretin-1 is at least partially activated by a reactive homeostatic mechanism, it is likely also regulated by the circadian pacemaker. In the squirrel monkey, hypocretin-1 works in opposition to the accumulating sleep drive during the day to maintain a constant level of wake.