Inhibition of phenylethanolamine-N-methyltransferase and brain-stimulated reward.

The centrally active inhibitors of phenylethanolamine-N-methyl transferase (PNMT; E.C. 2.1.1.28), the terminal enzyme for epinephrine biosynthesis in the brain, produced dose-related decreases in rats of responding for rewarding brain stimulation in adult male rats. Decreases occurred at dosages that did not produce measurable neurologic impairment. This suggests a possible role for central epinephrine-containing neurons in the maintenance of reward-mediated behaviors.