Maternal exercise shifts adiposity distribution in offspring towards energy burning brown fat

Abstract

Human epidemiological and animal studies show the maternal in utero environment significantly impacts offspring development. This includes sedentary lifestyle, which is linked to developmental programming of metabolic dysfunction. The aim of this study was to investigate metabolic outcomes in offspring of sedentary mice versus mice that exercised in pregnancy. C57BL/6J female mice were placed on control diet and allocated to sedentary (SED) versus voluntary running wheel exercise (EX) cages. Voluntary wheel running was allowed 2 weeks prior to breeding and throughout weaning. Offspring underwent body composition measurement and insulin and glucose tolerance tests at 6 and 12 weeks of age, were placed in an indirect calorimetry system to assess energy balance at 14 weeks, and were euthanized for collection of adipose depots at 16 weeks. Outcomes were analyzed by two-way ANOVA to assess effects of exercise, sex, and their interaction. We studied metabolic function in 11 male SED, 13 female SED, 15 male EX, and 13 female EX offspring. While body mass and adiposity were similar among groups, EX mice had less subcutaneous white adipose (% body mass: 1.26±0.09 male SED vs. 0.87±0.06 male EX vs. 1.15±0.11 female SED vs. 0.95 ±0.04 female EX; PSex=0.871, PEX=0.001, PInt=0.237) and more brown adipose (% body mass: 0.31±0.03 male SED vs. 0.47±0.05 male EX vs. 0.27±0.02 female SED vs. 0.48 ±0.05 female EX; PSex=0.704, PEX=0.001, PInt=0.527). There were no differences in fasting glucose and insulin levels, insulin sensitivity, glucose tolerance, or measures of energy balance (e.g., food intake, energy expenditure) among groups. These data suggest that despite no change in overall body mass or body composition, maternal exercise shifts adiposity distribution of offspring away from energy storing white fat towards energy burning brown fat. This change may impact energy metabolism over the lifespan given increasing evidence for advantageous metabolic adaptations with increased brown fat.