Meeting Abstract
Locomotor activity is a key element of most animal behaviors. Individual variation in the amount of voluntary exercise (VE) and spontaneous physical activity (SPA), in both humans and laboratory rodents, is known to be heritable, but also affected by numerous environmental factors. Early-life experiences that may have long-lasting effects are one potentially important aspect of environmental factors. The current experiment was designed to explore genetic, environmental, and early-life effects in the context of a long-term selection experiment that includes 4 lines of high runner (HR) mice, selectively bred for >75 generations for voluntary wheel-running as young adults, as well as their 4 non-selected control lines. In the present experiment, we altered VE by granting wheel access or not and administered either standard or Western diet (WD) during the juvenile period from weaning to 6 weeks of age (sexual maturity), followed by housing without wheels and with standard chow. ~2 months later, we measured wheel-running behavior (VE), home-cage activity (SPA), and several potentially related physiological and behavioral traits. As adults, HR mice ran more than C regardless of treatment, but linetype also had statistically significant interactions with both early-life wheel access and diet. For example, juvenile wheel access increased adult VE for C mice, but deceased it for HR, whereas juvenile WD increased adult VE for HR but not for C mice. Juvenile wheel access decreased adult relative heart mass, but increased relative triceps surae muscle mass, fat mass, and blood [glucose]. These and other results demonstrate that both juvenile exercise environment and diet can have long-lasting effects on adult activity behaviors and related phenotypes.
