Blood oxygenation level-dependent response to intragastric load of corn oil emulsion in conscious rats.

The postingestive actions after intragastric or oronasal stimulation of fat have been well investigated. The blood oxygenation level-dependent (BOLD) signal changes, however, after intragastric load of corn oil emulsion have yet to be elucidated. Here, using functional magnetic resonance imaging, we investigated the BOLD signal response to gut corn oil emulsion in nonanesthetized rats. Intragastrically infused 7% corn oil emulsion induced a BOLD signal increase in several brain regions, including the bilateral amygdala, hippocampus and the ventral tegmental area. These results indicate that the limbic system responds to gut corn oil emulsion and that activation of this system could promote the reinforcing action for food with high fat content.