title: Context modulates the expression of conditioned motor sensitization, cellular activation and synaptophysin immunoreactivity.
abstract: We tested the hypothesis that amphetamine (AMPH)-induced conditioned motor sensitization is accompanied by cellular activation (measured by Fos immunoreactivity) and synaptophysin immunoreactivity in reward-related brain areas. Forty-eight rats were tested for conditioned motor sensitization using a conditioning paradigm that was performed in a three-chambered apparatus. Rats underwent two drug pairings with 1.0 mg/kg AMPH in one outer chamber and, on alternate days, were paired with saline in the other. On the fifth day, relative to the first AMPH treatment, AMPH administration increased motor activity in the AMPH-paired context but not in the saline-paired context. Relative to the first saline treatment, saline on the fifth day produced a conditioned increase in motor activity when given in the chamber previously paired with AMPH, and saline given in the saline-paired context produced a conditioned decrease in motor activity. AMPH administered in the AMPH-paired context increased the density of both Fos and synaptophysin immunoreactivity in the dentate gyrus, cornu ammonis (CA)1, CA3, basolateral amygdala and dorsolateral striatum. This pairing between context and drug increased Fos but not synaptophysin immunoreactivity in the nucleus accumbens core and shell. Saline administered in the AMPH-paired context increased the density of Fos immunoreactivity in the basolateral amygdala and nucleus accumbens core. These data indicate that the basolateral amygdala-nucleus accumbens core pathway is necessary for the context-elicited conditioned motor responses, while the hippocampus encodes the spatial context.
authors.affiliation: Department of Cellular and Molecular Pharmacology, Rosalind Franklin University of Medicine and Science, 3333 Green Bay Road, North Chicago, IL 60064, USA. david.rademacher@rosalindfranklin.edu
authors.forename: David J
authors.initials: DJ
authors.lastname: Rademacher
authors.forename: T Celeste
authors.initials: TC
authors.lastname: Napier
authors.forename: Gloria E
authors.initials: GE
authors.lastname: Meredith
mesh_terms: D018759:Adrenergic Uptake Inhibitors / Q000494:pharmacology; D000661:Amphetamine / Q000494:pharmacology*; D000679:Amygdala / Q000187:drug effects / Q000378:metabolism; D000818:Animals; D003213:Conditioning, Psychological / Q000187:drug effects* / Q000502:physiology; D018891:Dentate Gyrus / Q000187:drug effects / Q000378:metabolism; D006624:Hippocampus / Q000187:drug effects / Q000378:metabolism; D007150:Immunohistochemistry; D008297:Male; D009043:Motor Activity / Q000187:drug effects* / Q000502:physiology; D017072:Neostriatum / Q000187:drug effects / Q000378:metabolism; D009434:Neural Pathways / Q000187:drug effects* / Q000378:metabolism; D009714:Nucleus Accumbens / Q000187:drug effects* / Q000378:metabolism; D016760:Proto-Oncogene Proteins c-fos / Q000187:drug effects / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D009435:Synaptic Transmission / Q000187:drug effects / Q000502:physiology; D016708:Synaptophysin / Q000187:drug effects* / Q000378:metabolism*; D013687:Telencephalon / Q000187:drug effects* / Q000378:metabolism
chemical_list: D018759:Adrenergic Uptake Inhibitors; D016760:Proto-Oncogene Proteins c-fos; D016708:Synaptophysin; D000661:Amphetamine