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Serotonin agonists (for the acute treatment of attacks) and antagonists (for prophylactic treatment) are the most widely used drugs to treat migraine. However, their effectiveness is not complete and their use is limited by side effects. The activity and presumptive mode of action of these drugs provide support for the role of serotonin in the pathophysiology of migraine and suggest that the trigeminal-vascular system is at the center of the attack; however, other factors and mechanisms may also be involved.

The vascular effects induced by histamine and their inhibition by cyproheptadine have been studied on rabbit aortic strips. On arteries pre-contracted with phenylephrine, histamine provokes a dose-dependent relaxation only when mepyramine is present in the bath. This effect is independent of the integrity of endothelium. Cyproheptadine (10(-9) M) required the presence of cimetidine to give a parallel antagonism of the histamine curve (Kb: 0.32 nM). At higher concentrations of cyproheptadine (3 X 10(-9) and 10(-8) M) the effect was non-competitive. Cyproheptadine displaced to the right in a parallel manner the dose response curve of noradrenaline (pA2 = 6.6) and of serotonin (pA2 = 8.9) and reduced the contracting effects of KCl (IC50 = 7.3 10(-7) M) and of angiotensin II (IC50 = 4 X 10(5) M).

In order to assess the role of inflammation and its components in spontaneous cure of Strongyloides ratti infestation, rats were treated with non-steroid anti-inflammatory agents (indometacin; sodium salicylate) or with antagonists of certain mediators (dexchlorpheniramin; cyproheptadin, promethazin). Results were compared with those obtained in similar treatments of rats infested by other Nematoda which also give rise to spontaneous cure: especially Trichinella spiralis, and Nippostrongylus brasiliensis. Coordinating the various findings made it possible to devise a pattern accounting for the chain of reactions that lead to rejection of the parasite.