The brain serotonergic system in the affective disorders

Abstract

1. 1. An alteration in the brain serotonergic system in individuals with depression, and possibly mania, has been proposed on the basis that these patients have reduced 5-hydroxyindoleacetic acid levels in cerebrospinal fluid. 2. 2. Reduced brain serotonin concentrations have also been observed in some studies of suicides. 3. 3. Other investigations of serotonin-related functions in depressed patients have yielded equivocal results, although potentiation of the therapeutic effects of antidepressant drugs by L-tryptophan, and their reversal by p-chlorophenylalanine, are in agreement with animal pharmacological studies indicating that antidepressant drugs act in part via serotonergic mechanisms. 4. 4. The biochemical basis for the suggested serotonergic system alterations in the affective disorders remains unknown. 5. 5. Additional basic information is needed on (a) the storage, transport and synthesis of indoleamines, (b) adaptational mechanisms within the system and their relationships to other neurotransmitter systems, and (c) correlations with behavior in animals and man. 6. 6. Such studies may further our understanding of the role which the serotonergic system alterations may play in the affective disorders.