title: Stimuli associated with the presence or absence of amphetamine regulate cytoskeletal signaling and behavior.
abstract: Drug-paired stimuli rapidly enlarge dendritic spines in the nucleus accumbens (NAcc). While increases in spine size and shape are supported by rearrangement of the actin cytoskeleton and facilitate the synaptic expression of AMPA-type glutamate receptors, it remains unclear whether drug-related stimuli can influence signaling pathways known to regulate these changes in spine morphology. These pathways were studied in rats trained on a discrimination learning paradigm using subcellular fractionation and protein immunoblotting to isolate proteins within dendritic spine compartments in the NAcc shell. An open field chamber was repeatedly associated with amphetamine in one group (Paired) and explicitly unpaired with amphetamine in another (Unpaired). Rats in a third group were exposed to the open field but never administered amphetamine (Control). When administered saline and returned to the open field one week later, Paired rats as expected displayed a conditioned locomotor response relative to rats in the other two groups. NAcc shell tissues were harvested immediately after this 30-minute test. Re-exposing Paired rats to the drug-paired excitatory context significantly decreased p-GluA2(S880), an effect consistent with reduced internalization of this subunit and increased spine proliferation in these rats. In contrast, re-exposing Unpaired rats to the drug-unpaired context, capable of inhibiting conditioned responding in these animals, significantly decreased levels of both actin binding protein Arp2/3 and p-cofilin, consistent with spine volatility, shrinkage, and inhibition of spine proliferation in these rats. These findings show that contextual stimuli previously associated with either the presence or absence of amphetamine differentially regulate cytoskeletal signaling pathways in the NAcc.
authors.affiliation: Department of Psychology, University of Michigan, Ann Arbor, MI, USA; Committee on Neurobiology, University of Chicago, Chicago, IL, USA. Electronic address: bfsinger@uchicago.edu.
authors.forename: Bryan F
authors.initials: BF
authors.lastname: Singer
authors.affiliation: Department of Psychiatry and Behavioral Neuroscience, University of Chicago, Chicago, IL, USA.
authors.forename: Nancy
authors.initials: N
authors.lastname: Bubula
authors.affiliation: Department of Psychiatry and Behavioral Neuroscience, University of Chicago, Chicago, IL, USA.
authors.forename: Magdalena M
authors.initials: MM
authors.lastname: Przybycien-Szymanska
authors.affiliation: Department of Psychiatry and Behavioral Neuroscience, University of Chicago, Chicago, IL, USA.
authors.forename: Dongdong
authors.initials: D
authors.lastname: Li
authors.affiliation: Committee on Neurobiology, University of Chicago, Chicago, IL, USA; Department of Psychiatry and Behavioral Neuroscience, University of Chicago, Chicago, IL, USA.
authors.forename: Paul
authors.initials: P
authors.lastname: Vezina
mesh_terms: D000661:Amphetamine / Q000494:pharmacology*; D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects*; D000697:Central Nervous System Stimulants / Q000494:pharmacology*; D003599:Cytoskeleton / Q000187:drug effects*; D049229:Dendritic Spines / Q000187:drug effects; D004193:Discrimination Learning / Q000187:drug effects; D008297:Male; D009043:Motor Activity / Q000187:drug effects; D009714:Nucleus Accumbens / Q000187:drug effects; D051381:Rats; D017207:Rats, Sprague-Dawley; D018091:Receptors, AMPA / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects*; D013347:Subcellular Fractions / Q000187:drug effects / Q000378:metabolism
chemical_list: D000697:Central Nervous System Stimulants; D018091:Receptors, AMPA; D000661:Amphetamine; C104722:glutamate receptor ionotropic, AMPA 2
keywords: AMPA; Actin; Arp2/3; Cofilin; Conditioning; Nucleus accumbens