Uncoupling proteins and sleep deprivation.
In both humans and animals sleep deprivation (SD) produces an increase in food intake and in energy expenditure (EE). The increase in EE is a core element of the SD syndrome and, in rats, is negatively correlated with survival rate. However, the mechanisms involved are not understood. A large component of resting EE is accounted for by the mitochondrial proton leak, which is mediated by uncoupling proteins (UCPs). We measured UCP2, UCP3, and UCP5 mRNA levels in rats during the spontaneous sleep/waking cycle and after short (8 hours) and long (7 days) SD. During spontaneous sleep and waking there was no change in the level of mitochondrial uncoupling as measured by UCPs expression, either in the brain or in peripheral tissues. During SD, by contrast, UCP3 expression in skeletal muscle was elevated, but the increase was similar, compared to sleep, after both short-term and long-term SD. UCP2 expression, on the other hand, was strongly increased in the liver and skeletal muscle of long-term sleep deprived animals and much less so, or not at all, in yoked controls or in rats that lost only 8 hours of sleep. Since the skeletal muscle is the largest tissue in the body, an elevated muscular expression of UCP2 is likely to affect the overall resting EE and may thus contribute to its increase after SD.
Cirelli
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Department of Psychiatry, University of Wisconsin-Madison, 6001 Research Park Blvd, Madison WI 53719, USA. ccirelli@wisc.edu
Tononi
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D000818:Animals; D001921:Brain / Q000378:metabolism; D002352:Carrier Proteins / Q000235:genetics; D002940:Circadian Rhythm / Q000235:genetics; D004435:Eating / Q000235:genetics; D004734:Energy Metabolism / Q000235:genetics*; D007473:Ion Channels; D008099:Liver / Q000378:metabolism; D008297:Male; D026901:Membrane Transport Proteins / Q000235:genetics*; D008928:Mitochondria / Q000235:genetics / Q000378:metabolism*; D033681:Mitochondrial Membrane Transport Proteins; D024101:Mitochondrial Proteins / Q000235:genetics*; D000071245:Mitochondrial Uncoupling Proteins; D018482:Muscle, Skeletal / Q000378:metabolism; D009419:Nerve Tissue Proteins / Q000235:genetics; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D011921:Rats, Inbred WKY; D012890:Sleep / Q000235:genetics; D012892:Sleep Deprivation / Q000235:genetics / Q000378:metabolism*; D000071246:Uncoupling Protein 2; D000071247:Uncoupling Protein 3; D015854:Up-Regulation / Q000235:genetics*; D014851:Wakefulness / Q000235:genetics
D002352:Carrier Proteins; D007473:Ion Channels; D026901:Membrane Transport Proteins; D033681:Mitochondrial Membrane Transport Proteins; D024101:Mitochondrial Proteins; D000071245:Mitochondrial Uncoupling Proteins; D009419:Nerve Tissue Proteins; D012333:RNA, Messenger; C492125:Slc25a14 protein, rat; C000604389:UCP2 protein, human; C000604392:UCP3 protein, human; C000604391:Ucp2 protein, rat; C000604394:Ucp3 protein, rat; D000071246:Uncoupling Protein 2; D000071247:Uncoupling Protein 3