A Vexing Hormone–Serotonin

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SEVERAL years ago we wrote editorially that serotonin should provide “tenure for the pharmacologist.” As it has turned out, this prophecy was gross understatement. And, despite many hundreds of publications on serotonin since, it is frustrating to have to record now that it is still not known surely what physiologic role or roles serotonin may play. It has been referred to appropriately as “a hormone in search of a function,” and it should be of succor to the pharmacologic and allied sciences for some time to come. It occurs normally in several body tissues, and it can be shown to have powerful effects on nearly all biologic systems. The sorting out of what normal and abnormal functions serotonin may mediate is a large and intriguing task for the future, but it is timely now to offer a progress report on the present status of our knowledge concerning some of the effects of serotonin on the cardiovascular system.

Serotonin was first isolated in the Research Division. This fact is generally known—but it is not so well known that the discovery is a fine example of serendipity. A series of experiments was not going well because of interference by a vasoconstrictor material that appeared when blood clotted. A plan was devised to isolate this interfering “nuisance” in order that the experiments could proceed— and it turned out to be 5-hydroxytryptamine—serotonin. Fortunately, the importance of the isolation was recognized and was reported in 1948. Of course, the then more important . . .