[Progress of clinical pharmacology in essential headaches].

By testing venomotor receptors (venous-constriction test), it was possible to show a potentiation of the venous constriction effect of serotonin by methysergide and ergotamine. This 5-HT potentiation was observed only when these drugs were sampled in concentrations similar to those in therapeutic use. When ergotamine and methysergide are sampled in concentrations higher than those used in clinical practice, the expected 5-HT antagonist effect is clearly evident. We could therefore conclude that methysergide and ergotamine can be considered pro-serotonin and not anti-serotonin drugs. The pro-serotonin effect of methysergide and ergotamine might take place peripherally on vasomotor or sensitive receptors and/or at a CNS level, making up for the lack of serotonin which, according to the central theory of essential headache, provokes the painful cephalic syndrome.