THE 5-HYDROXYTRYPTAMINE-NITRIC OXIDE CONNECTION - THE KEY LINK IN THEINITIATION OF MIGRAINE

The evidence for an involvement of 5-hydroxytryptamine (5-HT) and nitr ic oxide (NO) in the initiation of migraine is reviewed. Based on this , the following scenario is proposed. Endogenous 5-HT, arising perhaps from platelets but more likely from perivascular 5-HT-containing neur ons in response to different types of ''stress'', would activate 5-HT2 B/5-HT2C receptors on endothelial cells of the cerebral vasculature to release NO. Nitric oxide would, by directly activating sensory neuron s, induce neurotransmitter release, plasma extravasation, pain and hyp eralgesia. The result would be induction of the ''sterile'' inflammato ry response, believed to be the key step in the development of migrain e.