title: Moderate Alcohol Drinking and the Amygdala Proteome: Identification and Validation of Calcium/Calmodulin Dependent Kinase II and AMPA Receptor Activity as Novel Molecular Mechanisms of the Positive Reinforcing Effects of Alcohol.
abstract: BACKGROUND
  Despite worldwide consumption of moderate amounts of alcohol, the neural mechanisms that mediate the transition from use to abuse are not fully understood.
  
  
  METHODS
  Here, we conducted a high-throughput screen of the amygdala proteome in mice after moderate alcohol drinking (n = 12/group) followed by behavioral studies (n = 6-8/group) to uncover novel molecular mechanisms of the positive reinforcing properties of alcohol that strongly influence the development of addiction.
  
  
  RESULTS
  Two-dimensional difference in-gel electrophoresis with matrix assisted laser desorption ionization tandem time-of-flight identified 29 differentially expressed proteins in the amygdala of nondependent C57BL/6J mice following 24 days of alcohol drinking. Alcohol-sensitive proteins included calcium/calmodulin-dependent protein kinase II alpha (CaMKIIα) and a network of functionally linked proteins that regulate neural plasticity and glutamate-mediated synaptic activity. Accordingly, alcohol drinking increased α-amino-3-hydroxy-5-methyl-4-isooxazole receptor (AMPAR) in central amygdala (CeA) and phosphorylation of AMPAR GluA1 subunit at a CaMKII locus (GluA1-Ser831) in CeA and lateral amygdala. Further, CaMKIIα-Thr286 and GluA1-Ser831 phosphorylation was increased in CeA and lateral amygdala of mice that lever-pressed for alcohol versus the nondrug reinforcer sucrose. Mechanistic studies showed that targeted pharmacologic inhibition of amygdala CaMKII or AMPAR activity specifically inhibited the positive reinforcing properties of alcohol but not sucrose.
  
  
  CONCLUSIONS
  Moderate alcohol drinking increases the activity and function of plasticity-linked protein networks in the amygdala that regulate the positive reinforcing effects of the drug. Given the prominence of positive reinforcement in the etiology of addiction, we propose that alcohol-induced adaptations in CaMKIIα and AMPAR signaling in the amygdala may serve as a molecular gateway from use to abuse.
authors.affiliation: Departments of Curriculum in Neurobiology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina.
authors.forename: Michael C
authors.initials: MC
authors.lastname: Salling
authors.affiliation: Bowles Center for Alcohol Studies, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina.
authors.forename: Sara P
authors.initials: SP
authors.lastname: Faccidomo
authors.affiliation: Departments of Curriculum in Neurobiology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina.
authors.forename: Chia
authors.initials: C
authors.lastname: Li
authors.affiliation: Bowles Center for Alcohol Studies, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina.
authors.forename: Kelly
authors.initials: K
authors.lastname: Psilos
authors.affiliation: Bowles Center for Alcohol Studies, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina.
authors.forename: Christina
authors.initials: C
authors.lastname: Galunas
authors.affiliation: Departments of Curriculum in Neurobiology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina.
authors.forename: Marina
authors.initials: M
authors.lastname: Spanos
authors.affiliation: Departments of Curriculum in Neurobiology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina.
authors.forename: Abigail E
authors.initials: AE
authors.lastname: Agoglia
authors.affiliation: Departments of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina; Bowles Center for Alcohol Studies, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina; Departments of Curriculum in Neurobiology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina.
authors.forename: Thomas L
authors.initials: TL
authors.lastname: Kash
authors.affiliation: Departments of Psychiatry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina; Departments of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina; Bowles Center for Alcohol Studies, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina; Departments of Curriculum in Neurobiology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina. Electronic address: chodge@med.unc.edu.
authors.forename: Clyde W
authors.initials: CW
authors.lastname: Hodge
mesh_terms: D000428:Alcohol Drinking / Q000009:adverse effects*; D000679:Amygdala / Q000378:metabolism*; D000818:Animals; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2 / Q000378:metabolism*; D000431:Ethanol / Q000494:pharmacology*; D018698:Glutamic Acid / Q000378:metabolism; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D009473:Neuronal Plasticity / Q000187:drug effects; D010766:Phosphorylation / Q000187:drug effects; D020543:Proteome / Q000378:metabolism; D018091:Receptors, AMPA / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects
chemical_list: D020543:Proteome; D018091:Receptors, AMPA; D000431:Ethanol; D018698:Glutamic Acid; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; C517671:Camk2a protein, mouse
keywords: AMPA; Addiction; Alcohol; Amygdala; CaMKII; CaMKII alpha; GluA1; Glutamate; Mice; Proteomics; Reinforcement; Self-administration