title: Whole-body metabolism varies across the estrous cycle in Sprague-Dawley rats.
abstract: Food intake in rats and other mammals is lowest at estrus and highest at diestrus. While much is known about the effects of different estrous phases on energy intake, as well as some of the metabolic effects the associated hormones exert, little has been reported about changes in whole-body metabolism that accompany those phases. This study investigates how energy expenditure (EE) and respiratory quotient (RQ) vary in intact female Sprague-Dawley rats (n=12) tested mid-light cycle over 2 h on days associated with estrus vs. diestrus. Rats showed small but reliable decreases in body weight on days associated with estrus, but not diestrus. EE was significantly increased by approximately 21% on the day associated with estrus compared to diestrus. At the same time, RQ was significantly decreased by approximately 7% on the day associated with estrus, indicating a relative shift to fat over carbohydrate as the energy substrate to support energetic needs. Future investigations of ingestive processes can integrate the present findings to investigate how gender differences in feeding and metabolism contribute to regulatory behaviors.
authors.affiliation: Department of Psychology, Wayne State University, 71 West Warren Avenue, Detroit, MI 48202, USA. gparker@sun.science.wayne.edu
authors.forename: G C
authors.initials: GC
authors.lastname: Parker
authors.forename: M E
authors.initials: ME
authors.lastname: McKee
authors.forename: C
authors.initials: C
authors.lastname: Bishop
authors.forename: D V
authors.initials: DV
authors.lastname: Coscina
mesh_terms: D000818:Animals; D004040:Dietary Carbohydrates / Q000008:administration & dosage; D004041:Dietary Fats / Q000008:administration & dosage; D004435:Eating / Q000502:physiology; D004734:Energy Metabolism / Q000502:physiology*; D004971:Estrus / Q000502:physiology*; D005260:Female; D005518:Food Preferences / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D004040:Dietary Carbohydrates; D004041:Dietary Fats