Mesolimbic dopaminergic system activity as a function of food reward: a microdialysis study

The mesolimbic dopaminergic system (MDS) has been shown to be implicated in feeding behaviors. The present experiment was conducted to examine the effects of the sensory properties of food ingested on MDS activity. Microdialysis coupled to high-performance liquid chromatography with electrochemical detection was employed to measure the extracellular levels of dopamine (DA) and its main metabolites (DOPAC and HVA) in the nucleus accumbens of freely moving rats. During microdialysis sessions rats had access or not to powdered foods varying in palatability: short cakes as highly palatable (HP) food and regular chow as low palatable (LP) food. In the absence of food, there were no alterations in extracellular levels of DA, DOPAC, and HVA. During feeding, DA rose significantly with a greater rise for the HP than the LP food. Levels of DOPAC and HVA only reached significance with the HP food. The results indicate that the MDS is activated on ingestion of food, and suggest that MDS activity is related to the rewarding properties of foods.