Distribution of 5-hydroxytryptamine and 5-hydroxyindoleacetic acid in human brain in relation to age, drug influence, agonal status and circadian variation.

The post-mortem brain concentrations of 5-hydroxytryptamine (5-HT) and 5-hydroxyindoleacetic acid (5-HIAA) were determined in 16 parts of the brain from patients with no history of neurologic, psychiatric or metabolic illness. The causes of death were either ischemic heart disease, infections disease, cancer or accidents. Forty-two men with a mean age of 57 years (range 18-95 years) and 19 women with a mean age of 62 years (range 23-79 years) were included. The influence of several factors were studied: brain weight, time between death and autopsy, storage time before chemical analysis, age, sex, agonal status, cerebral arteriosclerosis, cancer, opiate treatment and time of death during the day. Most correlations between the 5-HT concentrations in different brain parts were positive, the strongest correlations in the basal ganglia and the limbic system. No consistent pattern of age-related 5-HT changes were found. The females had significantly higher 5-HIAA concentrations in the cortex of the gyrus hippocampus. Final hypoxia seemed to decrease 5-HT concentrations. Opiate treatment reduced 5-HT and increased 5-HIAA concentrations. A marked circadian variation of 5-HT was found, most pronounced in the hypothalamus, the limbic system and some neocortical areas.