title: Effects of estrous cycles and ovarian steroids on body weight and energy expenditure in Syrian hamsters.
abstract: In Experiment 1, highly significant changes were observed over the estrous cycle in body weight gain, but not in food intake, daytime resting oxygen consumption or brown fat thermogenesis in Syrian hamsters. In Experiments 2 and 3, body weight and composition, food intake, resting oxygen consumption, and brown fat thermogenesis were measured following estradiol or estradiol plus progesterone treatment in ovariectomized hamsters. The significant changes in body weight could not be explained by changes in food intake, and were not accompanied by significant alterations in daytime oxygen consumption or brown fat thermogenic activity. In Experiment 4, resting oxygen consumption and body weight were measured every 6 hours over the estrous cycle. There was a striking absence of the usual nocturnal peak in resting oxygen consumption on the night of estrus (the night of the largest body weight gain). However, brown fat thermogenic activity did not differ among groups of hamsters killed on different nights of the estrous cycle. Estradiol-induced changes in energy storage may be mediated by changes in the daily rhythm of energy expenditure which are not dependent on alterations in brown fat thermogenesis.
mesh_terms: D002001:Adipose Tissue, Brown / Q000378:metabolism; D000818:Animals; D001835:Body Weight; D002940:Circadian Rhythm; D006224:Cricetinae; D003576:Electron Transport Complex IV / Q000378:metabolism; D004734:Energy Metabolism; D004958:Estradiol / Q000502:physiology*; D004971:Estrus / Q000502:physiology*; D005260:Female; D006153:Guanosine Diphosphate / Q000378:metabolism; D008647:Mesocricetus; D008928:Mitochondria / Q000378:metabolism; D009929:Organ Size; D010052:Ovariectomy; D010101:Oxygen Consumption; D011374:Progesterone / Q000502:physiology*
chemical_list: D006153:Guanosine Diphosphate; D011374:Progesterone; D004958:Estradiol; D003576:Electron Transport Complex IV