Drugs abused by humans are thought to activate areas in the ventral striatum of the brain
that engage the organism in important adaptive behaviors, such as eating. In support of this,
we report here that striatal regions of sugar-dependent rats show alterations in dopamine
and opioid mRNA levels similar to morphine-dependent rats. Specifically, after a chronic
schedule of intermittent bingeing on a sucrose solution, mRNA levels for the D2 dopamine
receptor, and the preproenkephalin and preprotachykinin genes were decreased in …