title: Glucocorticoids, aerobic physiology, and locomotor behavior in California mice.
abstract: The glucocorticoid hormones corticosterone (CORT) and cortisol influence numerous physiological, morphological, and behavioral functions. However, few studies have addressed possible relationships between individual differences in glucocorticoid concentrations and whole-animal performance or metabolism. Because CORT is important in glucose regulation and energy metabolism and can influence activity levels, we hypothesized that individual variation in baseline circulating CORT levels would correlate with individual differences in energy expenditure (routine and maximal), aerobic physiology, voluntary exercise on wheels, and organ masses. We tested this hypothesis in the California mouse (Peromyscus californicus). We collected data from 54 adult, colony-bred mice on baseline CORT levels (measured near both the circadian peak and the circadian trough), voluntary wheel running and its energetic costs, maximal oxygen consumption during forced treadmill exercise ([Formula: see text]), basal metabolic rate, and relative organ masses. We found surprisingly few statistically significant relationships among CORT, energy metabolism, behavior, and organ masses, and these relationships appeared to differ between males and females. These findings suggest that individual differences in baseline CORT levels are not an important determinant of voluntary activity levels or aerobic performance in California mice.
authors.affiliation: Department of Biology and Graduate Program in Evolution, Ecology, and Organismal Biology, University of California, Riverside, California 92521, USA. edlug001@ucr.edu
authors.forename: Elizabeth M
authors.initials: EM
authors.lastname: Dlugosz
authors.forename: Breanna N
authors.initials: BN
authors.lastname: Harris
authors.forename: Wendy
authors.initials: W
authors.lastname: Saltzman
authors.forename: Mark A
authors.initials: MA
authors.lastname: Chappell
mesh_terms: D000818:Animals; D001481:Basal Metabolism; D057906:Circadian Clocks / Q000502:physiology; D003345:Corticosterone / Q000097:blood / Q000502:physiology*; D004734:Energy Metabolism; D005260:Female; D008297:Male; D009043:Motor Activity / Q000502:physiology*; D009929:Organ Size / Q000502:physiology; D010101:Oxygen Consumption / Q000502:physiology; D010542:Peromyscus / Q000502:physiology*; D012044:Regression Analysis
chemical_list: D003345:Corticosterone