A spoonful of sugar: feedback signals of energy stores and corticosterone regulate responses to chronic stress.
To begin to understand the effects of chronic stress on food intake and energy stores, the effects of increased activity in the hypothalamo-pituitary-adrenal (HPA) axis and glucocorticoids (GCs) on the body and brain must first be understood. We propose two major systems that are both GC sensitive: a metabolic feedback that is inhibitory and a direct central GC drive. Under basal conditions, the metabolic feedback signal to brain is dominant, although infusion of GC into a lateral brain ventricle blocks the effects of the metabolic feedback. Chronic stress activates GC secretion and brain nuclear GC receptor occupancy, markedly changing the normal relationships between these two major corticosteroid-activated systems. The stressor-induced switch in the relative strengths of these signals determines subsequent brain regulation of stress responses (behavioral, neuroendocrine and autonomic outflows). The metabolic feedback effects of GCs are mimicked by voluntary sucrose ingestion in adrenalectomized rats, and experiments suggest that the metabolic feedback also inhibits the stressor-induced direct GC drive on brain. We speculate that the interaction between peripheral and central GC-sensitive signaling systems may be coupled through the inhibitory actions of endogenous opiatergic inputs on corticotropin-releasing factor (CRF) neurons.
Dallman
Mary F
MF
Department of Physiology, University of California San Francisco, Box 0444, San Francisco, CA 94143-0444, USA. dallman@itsa.ucsf.edu
Akana
Susan F
SF
Laugero
Kevin D
KD
Gomez
Francisca
F
Manalo
Sotara
S
Bell
M E
ME
Bhatnagar
Seema
S
D000315:Adrenalectomy; D000818:Animals; D001143:Arousal / Q000187:drug effects / Q000502:physiology*; D001341:Autonomic Nervous System / Q000187:drug effects / Q000502:physiology; D001921:Brain / Q000187:drug effects / Q000502:physiology; D003345:Corticosterone / Q000494:pharmacology / Q000502:physiology*; D004326:Drinking / Q000187:drug effects / Q000502:physiology; D004435:Eating / Q000187:drug effects / Q000502:physiology*; D004734:Energy Metabolism / Q000187:drug effects / Q000502:physiology*; D005246:Feedback / Q000502:physiology*; D005938:Glucocorticoids / Q000494:pharmacology / Q000502:physiology; D007030:Hypothalamo-Hypophyseal System / Q000187:drug effects / Q000502:physiology; D009042:Motivation; D010913:Pituitary-Adrenal System / Q000187:drug effects / Q000502:physiology; D051381:Rats; D011965:Receptors, Glucocorticoid / Q000187:drug effects / Q000502:physiology; D013315:Stress, Psychological / Q000503:physiopathology*; D013395:Sucrose / Q000008:administration & dosage*; D013649:Taste / Q000187:drug effects / Q000502:physiology*
D005938:Glucocorticoids; D011965:Receptors, Glucocorticoid; D013395:Sucrose; D003345:Corticosterone