Title | Effects of food restriction on expression of place conditioning and biochemical correlates in rat nucleus accumbens. |
Publication Type | Journal Article |
Year of Publication | 2016 |
Authors | Jung C, Rabinowitsch A, Lee WTing, Zheng D, de Vaca SCabeza, Carr KD |
Journal | Psychopharmacology (Berl) |
Volume | 233 |
Issue | 17 |
Pagination | 3161-72 |
Date Published | 2016 Sep |
ISSN | 1432-2072 |
Keywords | Animals, Brain, Conditioning, Psychological, Extinction, Psychological, Food, Food Deprivation, Male, Mitogen-Activated Protein Kinase 1, Mitogen-Activated Protein Kinase 3, Morphine, Naloxone, Narcotic Antagonists, Narcotics, Nucleus Accumbens, Phosphorylation, Rats, Rats, Sprague-Dawley, Receptors, AMPA |
Abstract | RATIONALE: 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. OBJECTIVES: This study tested whether food restriction increases persistence of morphine CPP and conditioned place aversions (CPA) induced by LiCl and naloxone-precipitated morphine withdrawal. MATERIALS AND METHODS: 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. RESULTS: 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. CONCLUSIONS: 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. |
DOI | 10.1007/s00213-016-4360-4 |
Alternate Journal | Psychopharmacology (Berl.) |
PubMed ID | 27376947 |
PubMed Central ID | PMC4982816 |
Grant List | R01 DA003956 / DA / NIDA NIH HHS / United States T32 GM007308 / GM / NIGMS NIH HHS / United States |
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