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Impact of genetic strain on body fat loss, food consumption, metabolism, ventilation, and motor activity in free running female rats
Citation:
Gordon, C., A. Johnstone, AND P. Phillips. Impact of genetic strain on body fat loss, food consumption, metabolism, ventilation, and motor activity in free running female rats . Physiology & Behavior. Elsevier B.V., Amsterdam, Netherlands, 153(1):56-63, (2016).
Impact/Purpose:
To select the best experimental model to study how exposure to environmental pollutants affects the development of obesity, this study was undertaken to identify the best genetic strain and gender for obesity studies. We followed the changes in body composition of the same animals from four different strain including males and females, from just after weaning until the end of their life span. We found marked effects of strain and gender on natural changes in body fat. These data will be useful in future studies on exposure to air pollution and obesity.
Description:
Nuclear magnetic resonance (NMR) based body composition analysis is an idea means of assessing changes in relative proportions of fat, lean, and fluid in rodents non invasively. While the data are not as accurate as convent ional chemical analysis, the systems allow one to follow longitudinally changes in body composition in the same animal over its lifetime. Such data would be important in the study of mechanisms of metabolic disorders. We endeavored to track changes in body composition of male and female Long-Evans (LE), Sprague-Daw ley (SD), Fischer (F34), and Brown Norway (BN) (BN) rats from post-weaning over a >2 year period. Percent fat of pre-weaned LE and SD rats is markedly higher compared to the other strains. LE and SD strains display near exponential increases in body fat from weaning to 8 months of age. Post-weaned F344 male and females show relatively low levels of %fat but, after 2 years, %fat of fema les is equal to that of SD and LE in females. BN rats displayed the highest levels of lean tissue and lowest levels of fat. Percent fat of BN increases at the slowest rate as they age. Percent fluid was consistently higher in males for all strains. Females tended to have higher %fat than males in LE, SD, and F344 strains. Overall, we conclude that assessing the changes in body fat as well as lean and fluid of various strains of male and female rats over their lifetime will be useful in research endeavors including mechanisms of obesity and metabolic disorders.
