title: Effects of energy expenditure and Ucp1 on photoperiod-induced weight gain in collard lemmings.
abstract: OBJECTIVE
  To determine the role of total energy expenditure (TEE) and its components in the ability of collared lemmings to increase weight in response to a decrease in photoperiod.
  
  
  METHODS
  Energy expenditure was measured by 24-hour indirect calorimetry concurrent with food-intake studies. TEE and resting and nonresting energy expenditure (REE and NREE, respectively) were adjusted for body weight by analysis of covariance (ANCOVA). Uncoupling protein 1 (Ucp1) mRNA levels from interscapular brown adipose tissue were determined by Northern blot.
  
  
  RESULTS
  TEE and REE of lemmings exposed to a short photoperiod for 10 days were significantly lower than that of lemmings exposed to a long photoperiod (p < 0.05), whereas NREE was not significantly different (p = 0.44). Ucp1 mRNA levels in interscapular brown adipose tissue were 50% lower in short- vs. long-photoperiod lemmings (p < 0.01). Ucp1 mRNA levels were positively related to REE (r2 = 0.79, p < 0.01). After adjustment of REE for differences in Ucp1 mRNA levels, there was no longer a significant difference attributable to photoperiod treatment (p = 0.54).
  
  
  CONCLUSIONS
  The results of this study indicate that the increase in body mass that occurs when collared lemmings are exposed to a short photoperiod may be primarily fueled by a decrease in REE and is correlated with a decrease in Ucp1 mRNA levels.
authors.affiliation: Department of Nutrition Sciences, The University of Alabama at Birmingham, 35294-3360, USA.
authors.forename: Charles Stephenson
authors.initials: CS
authors.lastname: Powell
authors.forename: Matthew L
authors.initials: ML
authors.lastname: Blaylock
authors.forename: Ruixue
authors.initials: R
authors.lastname: Wang
authors.forename: Heather L
authors.initials: HL
authors.lastname: Hunter
authors.forename: Gary L
authors.initials: GL
authors.lastname: Johanning
authors.forename: Tim R
authors.initials: TR
authors.lastname: Nagy
mesh_terms: D002001:Adipose Tissue, Brown / Q000737:chemistry; D000595:Amino Acid Sequence; D000818:Animals; D003411:Arvicolinae / Q000502:physiology*; D001483:Base Sequence; D015152:Blotting, Northern; D001823:Body Composition; D001831:Body Temperature; D001835:Body Weight; D002153:Calorimetry, Indirect; D002352:Carrier Proteins / Q000235:genetics / Q000502:physiology*; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000737:chemistry / Q000235:genetics; D004435:Eating; D004734:Energy Metabolism; D007473:Ion Channels; D008297:Male; D008565:Membrane Proteins / Q000235:genetics / Q000502:physiology*; D024101:Mitochondrial Proteins; D008969:Molecular Sequence Data; D017440:Photoperiod; D012333:RNA, Messenger / Q000032:analysis; D000071256:Uncoupling Protein 1; D015430:Weight Gain
chemical_list: D002352:Carrier Proteins; D018076:DNA, Complementary; D007473:Ion Channels; D008565:Membrane Proteins; D024101:Mitochondrial Proteins; D012333:RNA, Messenger; D000071256:Uncoupling Protein 1