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Alterations in AMPA receptor subunits and TARPs in the rat nucleus accumbens related to the formation of Ca2+-permeable AMPA receptors during the incubation of cocaine craving
Neuropharmacology (2011)
  • Carrie R. Ferrario, Rosalind Franklin University of Medicine and Science
  • Jessica A. Loweth, Rowan University School of Osteopathic Medicine
  • Mike Milovanovic, Rosalind Franklin University of Medicine and Science
  • Kerstin A. Ford, Rosalind Franklin University of Medicine and Science
  • Gregorio L. Galiñanes, Rosalind Franklin University of Medicine and Science
  • Li Jun Heng, Rosalind Franklin University of Medicine and Science
  • Kuei Y. Tseng, Rosalind Franklin University of Medicine and Science
  • Marina E. Wolf, Rosalind Franklin University of Medicine and Science
Abstract
Cue-induced cocaine seeking intensifies or incubates after withdrawal from extended access cocaine self-administration, a phenomenon termed incubation of cocaine craving. The expression of incubated craving is mediated by Ca²⁺-permeable AMPA receptors (CP-AMPARs) in the nucleus accumbens (NAc). Thus, CP-AMPARs are a potential target for therapeutic intervention, making it important to understand mechanisms that govern their accumulation. Here we used subcellular fractionation and biotinylation of NAc tissue to examine the abundance and distribution of AMPAR subunits, and GluA1 phosphorylation, in the incubation model. We also studied two transmembrane AMPA receptor regulatory proteins (TARPs), γ-2 and γ-4. Our results, together with earlier findings, suggest that some of the new CP-AMPARs are synaptic. These are probably associated with γ-2, but they are loosely tethered to the PSD. Levels of GluA1 phosphorylated at serine 845 (pS845 GluA1) were significantly increased in biotinylated tissue and in an extrasynaptic membrane-enriched fraction. These results suggest that increased synaptic levels of CP-AMPARs may result in part from an increase in pS845 GluA1 in extrasynaptic membranes, given that S845 phosphorylation primes GluA1-containing AMPARs for synaptic insertion and extrasynaptic AMPARs supply the synapse. Some of the new extrasynaptic CP-AMPARs are likely associated with γ-4, rather than γ-2. The maintenance of CP-AMPARs in NAc synapses during withdrawal is accompanied by activation of CaMKII and ERK2 but not CaMKI. Overall, AMPAR plasticity in the incubation model shares some features with better described forms of synaptic plasticity, although the timing of the phenomenon and the persistence of related neuroadaptations are significantly different.
Keywords
  • Calcium Channels,
  • Calcium Signaling,
  • Cocaine,
  • Cocaine-Related Disorders,
  • Dopamine Uptake Inhibitors,
  • Drug-Seeking Behavior,
  • Nerve Tissue Proteins,
  • Neurons,
  • Nucleus Accumbens,
  • Phosphorylation,
  • P Post-Translational Protein Processing,
  • Protein Subunits,
  • Protein Transport,
  • AMPA Receptors,
  • Substance Withdrawal Syndrome
Publication Date
January 12, 2011
DOI
10.1016/j.neuropharm.2011.01.021
Citation Information
Carrie R. Ferrario, Jessica A. Loweth, Mike Milovanovic, Kerstin A. Ford, et al.. "Alterations in AMPA receptor subunits and TARPs in the rat nucleus accumbens related to the formation of Ca2+-permeable AMPA receptors during the incubation of cocaine craving" Neuropharmacology Vol. 61 Iss. 7 (2011) p. 1141 - 1151 ISSN: 0028-3908
Available at: http://works.bepress.com/jessica-loweth/10/