title: Stimulation by voluntary exercise of adrenal glucocorticoid secretion in mature female hamsters.
abstract: The possibility that habitual voluntary running induces a chronic change in adrenal glucocorticoid synthesis and secretion was examined in freely running mature female hamsters, in whom this behavior accelerates growth, reduces body fat levels, and elevates core temperature. Hamsters were free to run on horizontal discs or in vertical wheels between 32 and 80 days, in 14L:10D or in 10L:14D photoperiods, and at the end of this period, corticosterone and cortisol steroidogenesis and serial plasma corticosterone concentrations during day and night were used as measures of the chronic stimulation of adrenal cortical activity. Habitual voluntary running significantly increased steroidogenesis of both glucocorticoids and plasma corticosterone concentrations and alone accounted for all the variance in enhanced synthesis and secretion of corticosterone. Acute exercise and/or the nocturnal phase of circadian period enhanced the chronic stimulatory effects of exercise on cortisol. Despite its voluntary and apparently stress-free nature, running induces chronic increases in basal glucocorticoid secretion in mature female hamsters. Putative oversecretion of corticotropin releasing factor in freely running hamsters could account for increased steroidogenesis, acceleration of growth, reduced body fat levels, and core temperature elevation.
authors.affiliation: Department of Movement Science, University of Michigan, Ann Arbor 48109-2214.
authors.forename: K T
authors.initials: KT
authors.lastname: Borer
authors.forename: L L
authors.initials: LL
authors.lastname: Bestervelt
authors.forename: M
authors.initials: M
authors.lastname: Mannheim
authors.forename: M B
authors.initials: MB
authors.lastname: Brosamer
authors.forename: M
authors.initials: M
authors.lastname: Thompson
authors.forename: U
authors.initials: U
authors.lastname: Swamy
authors.forename: W N
authors.initials: WN
authors.lastname: Piper
mesh_terms: D000302:Adrenal Cortex / Q000502:physiology*; D000818:Animals; D001835:Body Weight / Q000502:physiology; D002940:Circadian Rhythm / Q000502:physiology*; D003345:Corticosterone / Q000097:blood*; D006224:Cricetinae; D004734:Energy Metabolism / Q000502:physiology; D005260:Female; D006854:Hydrocortisone / Q000097:blood*; D009043:Motor Activity / Q000502:physiology*; D013254:Steroid 17-alpha-Hydroxylase / Q000502:physiology; D013255:Steroid 21-Hydroxylase / Q000502:physiology
chemical_list: D013255:Steroid 21-Hydroxylase; D013254:Steroid 17-alpha-Hydroxylase; D003345:Corticosterone; D006854:Hydrocortisone