Accumbens Dopamine Mediates the Rewarding Effect of Orosensory Stimulation by Sucrose

To investigate the hypothesis that central dopamine mediates the rewarding effect of orosensory stimulation by sucrose that increases eating, specific dopamine antagonists were administered prior to sham-feeding tests in which rats ingested various concentrations of sucrose. Sham feeding (SF) was used to preserve the orosensory stimulation of sucrose while it eliminated sucrose's postingestive effects. The antagonists decreased intake as a function of the concentration of sucrose. Microstructural analysis of licking demonstrated that the antagonists did not affect the motor performance of licking. Thus, the inhibitory effect of the antagonists on intake was due to a decrease in the rewarding effect of sucrose. Microdialysis experiments demonstrated that dopamine was released in the nucleus accumbens during SF and that the synaptic action of dopamine in the accumbens was necessary for the normal rewarding effect of orosensory stimulation by sucrose.