The neural substrates of amphetamine conditioned place preference: implications for the formation of conditioned stimulus-reward associations.
Associations formed between conditioned stimuli and drug reward are major contributors in human drug addiction. To better understand the brain changes that accompany this process, we used immunohistochemistry for c-Fos (a neuronal activity marker), synaptophysin (a marker for synaptogenesis) and tyrosine kinase B receptor (a neurotrophic factor receptor that mediates synaptic plasticity) to investigate the neural substrates of amphetamine-induced conditioned place preference in rats. Conditioned place preference was induced by both 1.0 mg/kg and 0.3 mg/kg doses of amphetamine. Furthermore, amphetamine conditioning increased the density of c-Fos-immunoreactive cells and these cells were fully colocalized with the tyrosine kinase B receptor in the dentate gyrus, CA1 field and basolateral amygdala. Amphetamine conditioning increased the density of synaptophysin-immunoreactive varicosities in all brain regions studied, except the nucleus accumbens shell and dorsolateral striatum. The degree of conditioned place preference was highly correlated with c-Fos-immunoreactive cell density in the basolateral amygdala and with the density of synaptophysin-immunoreactive varicosities in all mesolimbic regions studied. The latter correlation was particularly impressive for the ventral pallidum and basolateral amygdala. The formation of conditioned stimulus-amphetamine reward associations is accompanied by tyrosine kinase B receptor expression in the basolateral amygdala and dentate gyrus, CA1 and CA3 fields of the hippocampus. These data therefore suggest that the formation of conditioned stimulus-reward associations requires, at least in part, activation of amygdalar-hippocampal circuits.
Rademacher
David J
DJ
Department of Cellular and Molecular Pharmacology, Rosalind Franklin University of Medicine and Science, Chicago Medical School, 3333 Green Bay Road, North Chicago, IL 60064, USA.
Kovacs
Beatrix
B
Shen
Fei
F
Napier
T Celeste
TC
Meredith
Gloria E
GE
D000661:Amphetamine / Q000494:pharmacology*; D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects; D001921:Brain / Q000166:cytology; D002452:Cell Count / Q000379:methods; D000697:Central Nervous System Stimulants / Q000494:pharmacology*; D003216:Conditioning, Operant / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D007150:Immunohistochemistry / Q000379:methods; D008297:Male; D009474:Neurons / Q000187:drug effects* / Q000378:metabolism; D016760:Proto-Oncogene Proteins c-fos / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D020813:Receptor, trkB / Q000378:metabolism; D012201:Reward; D016708:Synaptophysin / Q000378:metabolism; D013997:Time Factors
D000697:Central Nervous System Stimulants; D016760:Proto-Oncogene Proteins c-fos; D016708:Synaptophysin; D000661:Amphetamine; D020813:Receptor, trkB