Abstract

Many animal experiments have documented the importance of increased and decreased levels of serotonin on serotoninergic neurons in the regulation of mood, temperature, sleep, aggression, and sexual behavior. In man, however, there is less evidence to document its role in regulating these same functions. Nature has provided an example of increased production of peripheral serotonin in the form of carcinoid tumors. Little attention has been accorded the changes in function of the central nervous system accompanying these tumors. Therefore we have reviewed the records of 22 patients with carcinoid to determine what clinical changes are observed and found clinical evidence consistent with low activity of brain serotonin. We have sought possible explanations for these findings.