Effects of early-onset voluntary exercise on adult physical activity and associated phenotypes in mice

Abstract

The purpose of this study was to evaluate the effects of early-life exercise on adult physical activity (wheel running, home-cage activity), body mass, food consumption, and circulating leptin levels in males from four replicate lines of mice selectively bred for high voluntary wheel running (High Runner or HR) and their four non-selected control (C) lines. Half of the mice were given wheel access shortly after weaning for three consecutive weeks. Wheel access was then removed for 52 days, followed by two weeks of adult wheel access for all mice. A blood sample taken prior to adult wheel testing was analyzed for circulating leptin concentration. Early-life wheel access significantly increased adult voluntary exercise on wheels during the first week of the second period of wheel access, for both HR and C mice, and HR ran more than C mice. During this same time period, activity in the home cages was not affected by early-age wheel access, and did not differ statistically between HR and C mice. Throughout the study, all mice with early wheel access had lower body masses than their sedentary counterparts, and HR mice had lower body masses than C mice. With wheel access, HR mice also ate significantly more than C mice. Early-life wheel access increased plasma leptin levels (adjusted statistically for fat-pad mass as a covariate) in C mice, but decreased them in HR mice. At sacrifice, early-life exercise had no statistically significant effects on visceral fat pad, heart (ventricle), liver or spleen masses (all adjusted statistically for variation in body mass). Results support the hypothesis that early-age exercise in mice can have at least transitory positive effects on adult levels of voluntary exercise, in addition to reducing body mass, and may be relevant for the public policy debates concerning the importance of physical education for children.

Maternal exposure to Western diet affects adult body composition and voluntary wheel running in a genotype-specific manner in mice

“…However, we did find line- and sex-specific effects. Specifically, maternal WD increased wheel running for female offspring of HR line 7, which emphasizes our previous findings that the replicate HR lines have undergone somewhat different evolutionary paths under the same selection regime [46–48]. A sex-specific effect was also found in a study of rats with maternal high-fat diet, which reported less active male and more active female offspring when given free wheel access for one week [8].…”

“…Although HR lines experienced the same directional selection, each replicate line (and sexes within lines) differed in response time to the selection pressure and mean voluntary wheel running [45], as well as other phenotypes [30, e.g., 37, 46]. Thus, the replicate HR lines have had “multiple solutions” [47] and may be expected to differ in response to manipulation of maternal diet.…”

Spontaneous Physical Activity Defends Against Obesity

“…Recent evidence has explored whether other traits related to energy balance and physical activity are correlated with or influence SPA. For example, aerobic capacity does not correlate with SPA [56] while basal metabolic rate does [57], and the evidence is still mixed as to the effects of voluntary exercise on SPA [58–61]. Future challenges include the accurate measurement of SPA, its different components and NEAT, the possibility of measuring SPA and NEAT in group housed animals, and accurate comparison of the physiological effects and mechanisms of SPA between males and females.…”

Circulating levels of endocannabinoids respond acutely to voluntary exercise, are altered in mice selectively bred for high voluntary wheel running, and differ between the sexes

“…Readings are then averaged over a one-minute interval and reported using arbitrary units. We used a similar setup and calibration procedure as previously reported (Acosta et al 2015; Copes et al 2015). HCA was measured for 23 hours per day and all analyses were performed using a measure of sensor sensitivity as a covariate (Acosta et al 2015; Copes et al 2015).…”