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Opioid system in the medial prefrontal cortex mediates binge‐like eating
Author(s) -
Blasio Angelo,
Steardo Luca,
Sabino Valentina,
Cottone Pietro
Publication year - 2014
Publication title -
addiction biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.445
H-Index - 78
eISSN - 1369-1600
pISSN - 1355-6215
DOI - 10.1111/adb.12033
Subject(s) - nucleus accumbens , naltrexone , dynorphin , prefrontal cortex , proopiomelanocortin , endocrinology , amygdala , medicine , central nucleus of the amygdala , binge eating , brain stimulation reward , μ opioid receptor , opioid , psychology , opioid peptide , neuroscience , hypothalamus , dopamine , receptor , cognition , obesity
Binge eating disorder is an addiction‐like disorder characterized by excessive food consumption within discrete periods of time. This study was aimed at understanding the role of the opioid system within the medial prefrontal cortex ( mPFC) in the consummatory and motivational aspects of binge‐like eating. For this purpose, we trained male rats to obtain either a sugary, highly palatable diet ( P alatable rats) or a chow diet ( C how rats) for 1 hour/day. We then evaluated the effects of the opioid receptor antagonist, naltrexone, given either systemically or site‐specifically into the nucleus accumbens ( NAcc) or the mPFC on a fixed ratio 1 ( FR 1) and a progressive ratio schedule of reinforcement for food. Finally, we assessed the expression of the genes proopiomelanocortin ( POMC ), pro‐dynorphin ( PDyn ) and pro‐enkephalin ( PEnk ), coding for the opioids peptides in the NAcc and the mPFC in both groups. P alatable rats rapidly escalated their intake by four times. Naltrexone, when administered systemically and into the NAcc , reduced FR 1 responding for food and motivation to eat under a progressive ratio in both C how and P alatable rats; conversely, when administered into the mPFC , the effects were highly selective for binge eating rats. Furthermore, we found a twofold increase in POMC and a ∼50% reduction in PDyn gene expression in the mPFC of P alatable rats, when compared to control rats; however, no changes were observed in the NAcc . Our data suggest that neuroadaptations of the opioid system in the mPFC occur following intermittent access to highly palatable food, which may be responsible for the development of binge‐like eating.