Cholecystokinin in psychiatric research: a time for cautious excitement.

Cholecystokinin (CCK) is a peptide neurotransmitter that was originally isolated from the gastrointestinal system, but which is extensively and abundantly distributed within the central nervous system (CNS). Stimulated by the fairly recent recognition of receptor subtypes (A and B), and the development of receptor-specific antagonists, CCK research has been advancing rapidly; and its potential importance to psychiatric neuroscience has been increasingly recognized. CCK participates in the mediation of satiety; it interacts with dopamine and may modulate psychosis; it interacts with opiate systems and may be an "anti-analgesic": and it appears to play a role in the mediation of anxiety. Highly specific, CCK-B receptor antagonists have reached clinical trials and have potential clinical utility as anxiolytics, antipsychotics, anti-anorexics, or analgesics. There are grounds for excitement, but many obstacles remain to be overcome and clinical potential may not be fulfilled. However, we must not allow clinical disappointments to slow the accelerating pace of scientific progress in CCK research. Regardless of clinical payoffs, the CCK receptor is clearly of great importance to human CNS functioning and deserves ongoing scientific attention.