Maternal Exercise May Improve Metabolic Outcomes in Offspring in Mice

It is well recognized in both human epidemiological and animal studies that the maternal in utero environment has significant effects on development of offspring. This includes sedentary lifestyle, which has been linked to developmental programming of metabolic dysfunction. The aim of this study is to investigate metabolic outcomes in offspring of sedentary mice versus mice that exercised in pregnancy.C57BL/6J female mice were placed on a control diet and allocated to sedentary versus exercise cages at 17 weeks of age. Exercise cages included a voluntary running wheel, with daily exercise measured via activity trackers. Mice were allowed to exercise for 2 weeks prior to breeding and throughout weaning. Offspring underwent body composition measurement and insulin and glucose tolerance tests at 6 weeks of age. At 14-16 weeks of age, body composition was reassessed and mice were euthanized for tissue collection. Outcomes were analyzed between sedentary (SED) and exercise (EX) offspring using an unpaired t-test, with p<0.05 considered significant.We studied metabolic function in 10 SED and 9 EX offspring. Insulin sensitivity, measured as the area under the curve for the decrease in glucose over time in response to insulin, tended to be improved in EX versus SED offspring (-188 vs. 2991; p=0.062), with no difference in fasting glucose levels or glucose tolerance. While body mass was similar at end of study (23.4 EX vs. 23.1 SED; p=0.83), the percentage of subcutaneous white adipose tissue tended to be lower (0.94 EX vs. 1.67 SED; p=0.054) and brown adipose tissue was higher (0.57 EX vs. vs 0.30 SED; p<0.001) in EX offspring.These data suggest that maternal exercise may improve insulin sensitivity in offspring even under normal diet conditions. Further, despite similar body mass, offspring from mice that exercised during pregnancy had a shift in adipose depot composition with lower white adipose and higher brown adipose tissue. This change in body composition may have important implications for energy metabolism and is an important area of future study.