Metabolic Disorders: High Fat Diet (HFD) Challenge
HFD challenge is an accepted model for diet-induced obesity. Mice are fed 45% lard diet from weaning. Serial measurements of body composition (fat and lean body mass) are obtained by Quantitative Magnetic Resonance (QMR). HFD challenged mice are also given glucose tolerance and insulin tests.
Body fat is measured non-invasively and non-destructively by nuclear magnetic resonance (NMR) using the Bruker Minispec QMR Analyzer (Bruker Optics; Billerica, MA). The mouse is placed in a sample tube, which is inserted vertically into the Minispec. The entire mouse is exposed to various sequences of magnetic fields for 54 seconds. Signals are generated by the hydrogen nuclei as they spin about their axes. The amplitude, duration, and spatial distribution of these signals are related to the properties of fat and non-fat tissues; the Minispec software (v2.20 Rev.01) calculates the weights of fat and non-fat tissue based on these signals.
Displayed below is a sample graph of how body mass composition observations are presented. In comprehensive phenotypic data packages graphs are interactive. Raw or calculated data and statistics can be seen by clicking on points in the graph.
Figure illustrates total body weight (top left), total fat mass (top center), percent body fat (top right), and lean body mass (bottom center) of male mutant mice. Body mass composition values of wild type littermates (green circle), homozygous (red diamond), and recent historical wild type (purple line) mice are plotted against long-term historical values (± 2 standard deviations) for wild type animals (green shading). Recent wild type values are calculated from data collected within 60 days of current measures and long-term historical values are derived from data collected on more than 10,000 wild type mice.