Brain neurotransmitters in food and drug reward.

The discovery of brain peptides as neurotransmitters opens a new chapter in the study of feeding from a neural point of view. This article reviews current studies suggesting a limbic system framework of chemical neuroanatomy in which peptides play an important role in the control of eating and behavior reinforcement. In this framework, food intake and a variety of anorectic drugs (amphetamine, phenylpropanolamine, and fenfluramine) act on dopamine, norepinephrine, and serotonin systems that ascend from the hindbrain and midbrain to modulate feeding and satiety systems in the hypothalamus. Opiate peptides (enkephalin), and brain-gut peptides (neurotensin and CCK) influence feeding and satiety when injected in the hypothalamus and reinforce behavior when injected in the midbrain. Locomotor stimulants (amphetamine and phencyclidine) reinforce behavior by an action in the nucleus accumbens. Thus the behavioral effects of foods and drugs can now be partially understood in the context of functional neuroanatomy.