A longitudinal magnetic resonance imaging (MRI) study of differences in abdominal fat distribution between normal mice, and lean overexpressers of mitochondrial uncoupling protein-3 (UCP-3).
OBJECTIVE
To characterize evolution and distribution of abdominal adipose fat between 6 and 18 weeks of age in an animal model of energy consumption based on mice overexpressing the mitochondrial uncoupler protein 3 (UCP-3).


METHODS
T2-weighted multislice MRI was performed six times during the 12 week study; visceral, subcutaneous and intermuscular fat depots were quantified.


RESULTS
The overexpressor (UCP-3tg) mice consistently have less subcutaneous, visceral, interskeletal muscle and total fat throughout the experiment. Mean (standard error) volumes (ml) of the three distinct depots change between week 6 and week 18 as follows: wild type: subcutaneous 1.93 (0.28) to 6.18 (0.47), visceral 2.15 (0.34) to 6.37 (0.64), intermuscular 0.23 (0.04) to 0.53 (0.03); UCP-3tg: subcutaneous 1.47 (0.17) to 4.07 (0.57), visceral 1.18 (0.04) to 3.69 (0.59), intermuscular 0.23 (0.01) to 0.32 (0.04). Although they eat more (4.3 g compared with 3.4 g per day) the UCP-3tg's always weigh less than controls. In wild-type control animals, increases of all fat pools between week 6 and week 18 is highly significant, as it is for subcutaneous, visceral and total pools in the UCP-3tg animals. The UCP-3tg mice, however, show no significant absolute or relative increase in intermuscular fat; UCP-3 is predominantly overexpressed in skeletal muscle.


CONCLUSIONS
MRI provides an excellent approach to comparative studies of fat distribution in animal models of energy expenditure such as the UCP-3tg mouse.
Changani
K K
KK
GlaxoSmithKline, Welwyn, Hertfordshire, UK. kumar.changani@gsk.com
Nicholson
A
A
White
A
A
Latcham
J K
JK
Reid
D G
DG
Clapham
J C
JC
D000005:Abdomen; D000273:Adipose Tissue / Q000033:anatomy & histology*; D000375:Aging / Q000502:physiology*; D000818:Animals; D002352:Carrier Proteins / Q000378:metabolism*; D004734:Energy Metabolism; D007473:Ion Channels; D008137:Longitudinal Studies; D008279:Magnetic Resonance Imaging; D008297:Male; D051379:Mice; D024101:Mitochondrial Proteins; D018482:Muscle, Skeletal; D012867:Skin; D000071247:Uncoupling Protein 3
D002352:Carrier Proteins; D007473:Ion Channels; D024101:Mitochondrial Proteins; C000604393:Ucp3 protein, mouse; D000071247:Uncoupling Protein 3