Sleep deprivation of rats: the hyperphagic response is real.
OBJECTIVE
Chronic sleep deprivation of rats causes hyperphagia without body weight gain. Sleep deprivation hyperphagia is prompted by changes in pathways governing food intake; hyperphagia may be adaptive to sleep deprivation hypermetabolism. A recent paper suggested that sleep deprivation might inhibit ability of rats to increase food intake and that hyperphagia may be an artifact of uncorrected chow spillage. To resolve this, a palatable liquid diet (Ensure) was used where spillage is insignificant.


METHODS
Sleep deprivation of male Sprague Dawley rats was enforced for 10 days by the flowerpot/platform paradigm. Daily food intake and body weight were measured. On day 10, rats were transcardially perfused for analysis of hypothalamic mRNA expression of the orexigen, neuropeptide Y (NPY).


METHODS
Morgan State University, sleep deprivation and transcardial perfusion; University of Maryland, NPY in situ hybridization and analysis.


RESULTS
Using a liquid diet for accurate daily measurements, there was no change in food intake in the first 5 days of sleep deprivation. Importantly, from days 6-10 it increased significantly, peaking at 29% above baseline. Control rats steadily gained weight but sleep-deprived rats did not. Hypothalamic NPY mRNA levels were positively correlated to stimulation of food intake and negatively correlated with changes in body weight.


CONCLUSIONS
Sleep deprivation hyperphagia may not be apparent over the short term (i.e., < or = 5 days), but when extended beyond 6 days, it is readily observed. The timing of changes in body weight and food intake suggests that the negative energy balance induced by sleep deprivation prompts the neural changes that evoke hyperphagia.
Koban
Michael
M
Laboratory of Physiology, Richard N. Dixon Science Research Center, Department of Biology, Morgan State University, Baltimore, MD, USA.
Sita
Luciane V
LV
Le
Wei Wei
WW
Hoffman
Gloria E
GE
D000818:Animals; D001835:Body Weight / Q000235:genetics; D004734:Energy Metabolism / Q000235:genetics; D005786:Gene Expression Regulation / Q000235:genetics; D006963:Hyperphagia / Q000235:genetics / Q000523:psychology*; D007031:Hypothalamus / Q000473:pathology; D008297:Male; D009478:Neuropeptide Y / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics; D051381:Rats; D017207:Rats, Sprague-Dawley; D012892:Sleep Deprivation / Q000235:genetics / Q000523:psychology*
D009478:Neuropeptide Y; D012333:RNA, Messenger