Behavioral characterization of amygdala involvement in mediating intra-accumbens opioid-driven feeding behavior.

The present experiments were conducted to provide a more detailed behavioral analysis of the dissociable roles of the basolateral (BLA) and central nucleus (CeA) of the amygdala in mediating intra-accumbens (Acb) opioid-induced feeding of a high-fat diet. Confirming previous findings, temporary inactivation of the CeA with the GABAA agonist muscimol reduced DAMGO (D-Ala2-NMe-Phe4-Glyol5-enkephalin)-induced and baseline food intake, whereas intra-BLA muscimol selectively blocked only DAMGO-induced food intake, leaving baseline feeding intact. However, although inactivation of the BLA reduced DAMGO-induced food intake to control levels, this treatment led to exaggerated number and duration of food hopper entries after food intake had ended. A subsequent experiment under conditions of limited access to the diet found the identical pattern of behavior following intra-Acb administration of DAMGO, regardless of whether the BLA was inactivated. Last, BLA inactivation was shown to have no influence on feeding driven by a state of negative-energy balance (24-hr food deprivation), demonstrating a specific influence of the BLA on opioid-driven feeding. These findings suggest that BLA mediates palatability-driven feeding and that this influence is particular to the consummatory act of ingestion.