Article

Body Composition in a Seasonal Model of Obesity: Longitudinal Measures and Validation of DXA

Department of Biology, University of Alabama at Birmingham, Birmingham, Alabama 35294-3360, USA.
Obesity research (Impact Factor: 4.95). 12/2002; 10(11):1180-7. DOI: 10.1038/oby.2002.160
Source: PubMed

ABSTRACT Collared lemmings, Dicrostonyx groenlandicus, show rapid changes in body mass on a seasonal basis. The objective of this study was to measure longitudinal changes in body composition in animals undergoing photoperiod-induced weight gain and loss using DXA.
Adult, female collared lemmings exposed to either long (LD; 22 hours light/2 hours dark) or short (SD; 8 hours light/16 hours dark) photoperiods were anesthetized, and DXA was used to determine fat mass, lean tissue mass (LTM), total-body bone mineral content, and total-bone mineral density. After a baseline scan, one-half of the animals were transferred to the alternate photoperiod (SD-LD, weight loss; LD-SD, weight gain) and one-half remained on the same photoperiod (controls; SD-SD, LD-LD). Body composition was determined by DXA after 4 and 8 weeks. Animals were killed, and body composition was determined by carcass analysis. DXA-derived data were validated by comparing with carcass analysis.
Body composition by DXA was highly related to body composition measured by chemical analysis, thereby justifying the use of DXA. Lemmings in the SD-LD group lost weight, and this was reflected in measurable losses of fat and LTM. Lemmings in the LD-SD group gained weight, which was shown by measurable increases in fat, LTM and total-body bone mineral content.
Comparison of body composition determined by DXA to that by chemical extraction revealed that DXA is useful for measuring body composition. The longitudinal analysis revealed that collared lemmings undergo rapid changes in body composition when exposed to changes in photoperiod.

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