title: Wheel-running activity modulates circadian organization and the daily rhythm of eating behavior.
abstract: Consumption of high-fat diet acutely alters the daily rhythm of eating behavior and circadian organization (the phase relationship between oscillators in central and peripheral tissues) in mice. Voluntary wheel-running activity counteracts the obesogenic effects of high-fat diet and also modulates circadian rhythms in mice. In this study, we sought to determine whether voluntary wheel-running activity could prevent the proximate effects of high-fat diet consumption on circadian organization and behavioral rhythms in mice. Mice were housed with locked or freely rotating running wheels and fed chow or high-fat diet for 1 week and rhythms of locomotor activity, eating behavior, and molecular timekeeping (PERIOD2::LUCIFERASE luminescence rhythms) in ex vivo tissues were measured. Wheel-running activity delayed the phase of the liver rhythm by 4 h in both chow- and high-fat diet-fed mice. The delayed liver phase was specific to wheel-running activity since an enriched environment without the running wheel did not alter the phase of the liver rhythm. In addition, wheel-running activity modulated the effect of high-fat diet consumption on the daily rhythm of eating behavior. While high-fat diet consumption caused eating events to be more evenly dispersed across the 24 h-day in both locked-wheel and wheel-running mice, the effect of high-fat diet was much less pronounced in wheel-running mice. Together these data demonstrate that wheel-running activity is a salient factor that modulates liver phase and eating behavior rhythms in both chow- and high-fat-diet fed mice. Wheel-running activity in mice is both a source of exercise and a self-motivating, rewarding behavior. Understanding the putative reward-related mechanisms whereby wheel-running activity alters circadian rhythms could have implications for human obesity since palatable food and exercise may modulate similar reward circuits.
authors.affiliation: Department of Biological Sciences, Vanderbilt University Nashville, TN, USA.
authors.forename: Julie S
authors.initials: JS
authors.lastname: Pendergast
authors.affiliation: Department of Biological Sciences, Vanderbilt University Nashville, TN, USA.
authors.forename: Katrina L
authors.initials: KL
authors.lastname: Branecky
authors.affiliation: Gunn High School Palo Alto, CA, USA.
authors.forename: Roya
authors.initials: R
authors.lastname: Huang
authors.affiliation: 3VA Tennessee Valley Healthcare System Nashville, TN, USA ; Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, Vanderbilt University School of Medicine Nashville, TN, USA.
authors.forename: Kevin D
authors.initials: KD
authors.lastname: Niswender
authors.affiliation: Department of Biological Sciences, Vanderbilt University Nashville, TN, USA.
authors.forename: Shin
authors.initials: S
authors.lastname: Yamazaki
keywords: C57BL/6J; circadian; eating behavior; liver; metabolism; mice; obesity; voluntary exercise