Cholecyctokinin is a neuropeptide found in the gastrointestinal system and brain. Research has shown that it has various isolated fragments that may influence several important areas of human behavior, such as nociception, satiety and anxiety. Cholecystokinin receptors located in the central nervous system (CNS) are known as CCK-B receptors, and they have high affinity for the tetrapeptide fragment CCK-4. Anxiogenic effect of CKK-4 in humans suggested that it might be involved in pathogenesis of panic disorder, and opened new avenues of research into biological aspects of anxiety. Further research showed increased sensitivity of panic disorder patients to CCK-4 in comparison with normal volunteers. Next, substances capable of blocking CCK-B receptors (CCK-B antagonists) were synthesized and their action was evaluated. One of such antagonists, L-365,260 proved to be effective in blocking CCK-4 induced panic attacks in panic disorder sufferers. However, a pilot study failed to show the effectiveness of the same antagonist in decreasing the frequency of spontaneous panic attacks in panic disorder patients during the course of six weeks. Though CCK-B antagonists may prove to become great potential anxiolitic agents, more research has to be done in order to understand the mechanism of CCK-4 action as a neurotransmitter and its role in naturally occurring panic attacks Ethiology of panic disorder: a brief overviewPanic disorder, (PD) is a recognized psychiatric condition and is identified in DSM-III-R as a condition separate from other anxiety disorders. Its main feature is occurrence of unprovoked panic attacks, which happen at random and cannot be explained by the patients. These attacks of fear are closely associated with an overwhelming subjective feeling of anxiety in connection with unpleasant bodily sensations, such as increased heartbeat/palpitations, hot flushes/chills, abdominal distress, nausea, sweating, trembling/sha...
