Effects of energy expenditure and Ucp1 on photoperiod-induced weight gain in collard lemmings.
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.
Powell
Charles Stephenson
CS
Department of Nutrition Sciences, The University of Alabama at Birmingham, 35294-3360, USA.
Blaylock
Matthew L
ML
Wang
Ruixue
R
Hunter
Heather L
HL
Johanning
Gary L
GL
Nagy
Tim R
TR
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
D002352:Carrier Proteins; D018076:DNA, Complementary; D007473:Ion Channels; D008565:Membrane Proteins; D024101:Mitochondrial Proteins; D012333:RNA, Messenger; D000071256:Uncoupling Protein 1