Enhanced conditioned approach responses in transgenic mice with impaired glucocorticoid receptor function.
The long-term consequences of impaired glucocorticoid receptor (GR) function on reward-related learning were studied in transgenic mice with impaired GR function in a series of experiments taxing conditioned and unconditioned approach responses to stimuli predictive of food. There was a double-dissociation in that transgenic mice with impaired GR activity showed enhanced conditioned exploration in situations when stimuli predicted reward, while free-feeding food consumption over 24 h was reduced. Previous experiments have shown altered accumbens dopaminergic activity in these animals. In line with these findings, we observed an enhanced behavioural stimulation of transgenic mice following administration of d-amphetamine (2 mg/kg). This suggests that the increase in preparatory responses in transgenic mice may be mediated via an enhanced accumbens dopaminergic activity, possibly secondary to alterations in other brain systems.
Max Planck Institute of Psychiatry, Munich, Germany. steckler@mpipsykl.mpg.de
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D000818:Animals; D001070:Appetitive Behavior / Q000187:drug effects / Q000502:physiology*; D001143:Arousal / Q000187:drug effects / Q000502:physiology; D003216:Conditioning, Operant / Q000187:drug effects / Q000502:physiology*; D003913:Dextroamphetamine / Q000494:pharmacology; D004298:Dopamine / Q000502:physiology; D005106:Exploratory Behavior / Q000187:drug effects / Q000502:physiology; D008297:Male; D051379:Mice; D008815:Mice, Inbred Strains; D008822:Mice, Transgenic; D009042:Motivation; D009714:Nucleus Accumbens / Q000187:drug effects / Q000502:physiology; D011965:Receptors, Glucocorticoid / Q000187:drug effects / Q000235:genetics / Q000502:physiology*
D011965:Receptors, Glucocorticoid; D003913:Dextroamphetamine; D004298:Dopamine