Abstract
In a recent review of the structure and function of aminergic systems Iversen (1980) paid particular attention to the dopaminergic (DA) and noradrenergic neurones (NA) and only mentioned in passing those with 5HT as a transmitter. Although the original work on the low concentration of 5HIAA, the metabolite of 5HT, in CSF of depressed patients (Ashcroft et al, 1966) which brought serotonin to the attention of biological psychiatrists may not have stood the test of time, nevertheless, recent information on the behavioural consequences in animals of drugs and lesions which influence the output of the 5HT system suggests it plays a role in the development of pathological mood and behaviour in affective illness. This is reflected in the resurgence of clinical interest in antidepressant drugs designed to affect specifically the 5HT system and emphasizes the need to continue animal and clinical exploratory experiments on serotonergic function.