title: Glucocorticoids dose-dependently remodel energy stores and amplify incentive relativity effects.
abstract: To test whether glucocorticoids amplify incentive motivation, three groups of rats were adrenalectomized and replaced subcutaneously with pellets of corticosterone (B), containing 0, 30, or 80% B and cholesterol. A fourth group of sham adrenalectomized rats received cholesterol pellets. Animals were placed on a four-arm maze baited with 32% sucrose for 5-min daily sessions. After 7 days of minimal drinking on the maze at free-feeding weights, their body weights were gradually reduced to 90% of their free-feeding weights for the next 12 days (pre-shift phase). The sucrose concentration was reduced to 4% for the next 2 days (post-shift phase). B dose-dependently increased 32% sucrose intake, insulin secretion, and relative fat depots. Intake was reduced similarly in all groups following the shift to 4%, resulting in a relative B-dependent intake suppression following the shift to 4%. Videoscoring of locomotor activity indicated that search behaviors were not different between groups prior to the shift to 4%, whereas the increase in search behavior following the shift to 4% sucrose was entirely B-dependent. These data were predicted by a new model of chronic stress positing two regulatory axes on brain by glucocorticoids: one indirect axis by which glucocorticoids remodel energy stores to provide metabolic feedback and a direct axis whereby glucocorticoids act directly on brain to remodel appetitive structure.
authors.affiliation: Department of Physiology, University of California San Francisco, 94143-0444, USA. npecora@itsa.ucsf.edu
authors.forename: Norman
authors.initials: N
authors.lastname: Pecoraro
authors.forename: Francisca
authors.initials: F
authors.lastname: Gomez
authors.forename: Mary F
authors.initials: MF
authors.lastname: Dallman
mesh_terms: D000222:Adaptation, Physiological; D000315:Adrenalectomy; D000704:Analysis of Variance; D000818:Animals; D001070:Appetitive Behavior / Q000502:physiology*; D001823:Body Composition / Q000502:physiology*; D003345:Corticosterone / Q000008:administration & dosage / Q000502:physiology*; D004305:Dose-Response Relationship, Drug; D004343:Drug Implants; D004734:Energy Metabolism / Q000502:physiology*; D008297:Male; D009042:Motivation; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D004343:Drug Implants; D003345:Corticosterone