title: Effects of food restriction on expression of place conditioning and biochemical correlates in rat nucleus accumbens.
abstract: When ad libitum-fed rats undergo cocaine place preference conditioning (CPP) but are switched to food restriction for testing, CPP becomes resistant to extinction and correlates with phosphorylation of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor GluA1 at Ser845 in nucleus accumbens (NAc) core.
  
  
  
  This study tested whether food restriction increases persistence of morphine CPP and conditioned place aversions (CPA) induced by LiCl and naloxone-precipitated morphine withdrawal.
  
  
  
  Ad libitum-fed rats were conditioned with morphine (6.0 mg/kg, i.p.), LiCl (50.0/75.0 mg/kg, i.p.), or naloxone (1.0 mg/kg, s.c.) 22 h post-morphine (20.0 mg/kg, s.c.). Half of the subjects were then switched to food restriction. Daily testing resumed 3 weeks later, and brains were harvested when one diet group met extinction criterion. Western analyses probed for pSer845-GluA1, pERK1, and pERK2 in NAc.
  
  
  
  Food restriction increased persistence of morphine CPP and preference scores correlated with pSer845-GluA1 in NAc core and shell. LiCl CPA was curtailed by food restriction, yet pSer845-GluA1 and pERK2 were elevated in NAc core of food-restricted rats. Food restriction increased persistence of naloxone CPA and elevated pSer845-GluA1 in NAc core and shell, and aversion scores were negatively correlated with pERK1 and pERK2 in NAc core.
  
  
  
  These results suggest that food restriction prolongs responsiveness to environmental contexts paired with subjective effects of both morphine and morphine withdrawal. A mechanistic scheme, attributing these effects to upregulation of pSer845-GluA1, but subject to override by CPA-specific, pERK2-mediated extinction learning, is explored to accommodate opposite effects of food restriction on LiCl and naloxone CPA.
authors.affiliation: Department of Psychiatry, New York University School of Medicine, Alexandria Center for Life Sciences, 450 East 29th Street, New York, NY, 10016, USA.
authors.forename: Caroline
authors.initials: C
authors.lastname: Jung
authors.affiliation: Department of Psychiatry, New York University School of Medicine, Alexandria Center for Life Sciences, 450 East 29th Street, New York, NY, 10016, USA.
authors.forename: Ariana
authors.initials: A
authors.lastname: Rabinowitsch
authors.affiliation: Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, Alexandria Center for Life Sciences, 450 East 29th Street, New York, NY, 10016, USA.
authors.forename: Wei Ting
authors.initials: WT
authors.lastname: Lee
authors.affiliation: Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, Alexandria Center for Life Sciences, 450 East 29th Street, New York, NY, 10016, USA.
authors.forename: Danielle
authors.initials: D
authors.lastname: Zheng
authors.affiliation: Department of Psychiatry, New York University School of Medicine, Alexandria Center for Life Sciences, 450 East 29th Street, New York, NY, 10016, USA.
authors.forename: Soledad Cabeza
authors.initials: SC
authors.lastname: de Vaca
authors.affiliation: Department of Psychiatry, New York University School of Medicine, Alexandria Center for Life Sciences, 450 East 29th Street, New York, NY, 10016, USA. kc16@nyu.edu.|Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, Alexandria Center for Life Sciences, 450 East 29th Street, New York, NY, 10016, USA. kc16@nyu.edu.
authors.forename: Kenneth D
authors.initials: KD
authors.lastname: Carr
mesh_terms: D000818:Animals; D001921:Brain / Q000378:metabolism; D003213:Conditioning, Psychological / Q000187:drug effects*; D005108:Extinction, Psychological; D005502:Food; D005508:Food Deprivation / Q000502:physiology*; D008297:Male; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism; D009020:Morphine / Q000494:pharmacology*; D009270:Naloxone / Q000494:pharmacology; D009292:Narcotic Antagonists / Q000494:pharmacology; D009294:Narcotics / Q000494:pharmacology*; D009714:Nucleus Accumbens / Q000378:metabolism*; D010766:Phosphorylation; D051381:Rats; D017207:Rats, Sprague-Dawley; D018091:Receptors, AMPA / Q000378:metabolism*
chemical_list: D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D009020:Morphine; D009270:Naloxone; D009292:Narcotic Antagonists; D009294:Narcotics; D018091:Receptors, AMPA; C535149:Mapk1 protein, rat
keywords: Conditioned place aversion; Conditioned place preference; ERK; Food restriction; GluA1; Nucleus accumbens