[From inducers of panic attack to neurobiology of panic disorder]

Various provocative agents, including sodium lactate, carbon dioxide (CO2), caffeine, yohimbine and cholecystokinin (CCK), have been utilized as panicogenics in studies on healthy volunteers as well as in panic disorder patients. Most provocative agents are lacking in specificity, limiting their use in identifying neurotransmitter systems involved in panic attacks. CCK appears to offer several advantages over other challenge strategies since it is a putative neurotransmitter in the CNS, with its own neuronal pathways and receptors, and reliably provokes panic attacks in a dose-dependent manner. It is important to clarify the relationships between CCK and other neurotransmitter systems in order to further understand the neurobiology of panic disorder. The possible roles of some of these neurotransmitters in panic disorder are discussed in this review.