Increased dopamine metabolism in the nucleus accumbens and striatum following consumption of a nutritive meal but not a palatable non-nutritive saccharin solution.

This study examined the concentrations of dopamine (DA) and its metabolites homovanillic acid (HVA) and 3,4-dihydroxyphenylacetic acid (DOPAC) in the striatum and nucleus accumbens of rats that were either 20 hr food deprived or had been given 1 hr of access to food pellets, a liquid diet, or a palatable 0.4% saccharin solution. Significant increases were observed in the HVA/DA ratio in both structures following ingestion of either liquid diet or food pellets. Increases in the DOPAC/DA ratio were observed only after the ingestion of liquid diet. Ingestion of saccharin solution had no effect on any index of DA activity. These results indicate that the type of food ingested can influence dopaminergic responses to feeding, and argue against an exclusive role for motor or reward processes in determining DA activity.