Novel hypothesis for the cause of panic disorder via the neuroepithelial bodies in the lung

Panic disorder (PD) is a complex condition that is further complicated by its numerous inducers, which include hypercapnia, hypoxia, sodium lactate, caffeine and cholecystokinin. It seems unlikely that there are specific suffocation receptors for each of these inducers in the brain. The pulmonary neuroepithelial bodies (NEBs), which are situated at the bifurcation point of the small bronchi, act as storage cells for 5-hydroxytryptamine (5-HT) and sensors for suffocation. If we suppose that PD might represent an inflammation of the NEBs, bradykinin (BK) which augments the airway hyper-response to diverse indcers might cause these cells to release 5-HT along with peptides and panneuroendcrine markers from their dence-core secretory granules. It was revealed that BK with 5-HT could cross the blood-brain barrier (BBB). When 5-HT released from these cells along with BK cross the BBB, the release of 5-HT at the axonal terminals in the serotonergic neurons in the brain will be inhibited, since the 5-HT1 autoreceptor have a higher affinity for 5-HT than do the 5-HT2 receptors. The inhibition of 5-HT at the axonal terminal causes to suppress the periaqueductal gray matter, which inhibits flight reactions to impending danger, pain or asphyxia. In short, this serotonergic situation might bring about PD. According to this theory, the type of inducer that the PD patient is exposed to is unimportant as long as it stimulates the NEBs, and through the effect of 5-HT and BK, PD would be revaluated as a somatic disease that directly and reversibly affects the brain. (c) 2004 Elsevier Ltd. All rights reserved.