Monoamine metabolites in cerebrospinal fluid and serotonin uptake inhibition during treatment with chlorimipramine

The effects of chlorimipramine on the concentrations of the main metabolites of serotonin (5‐HT) norepinephrine (NE), and dopamine, i.e. 5‐hydroxyindoleacetic acid (5‐HIAA), 4‐hydroxy‐3‐methoxyphenyl glycol (HMPG), and homovanillic acid (HVA), respectively, were studied in cerebrospinal fluid from 14 depressed patients, and related to the serotonin‐ and NE uptake inhibiting activity in vitro of plasma drawnfrom the patients. Chlorimipramine inhibited the uptake of both transmitter amines in all patients. During treatment, the levels of 5‐HIAA and HMPG in cerebrospinal fluid (CSF) were significantly reduced. HVA levels were reduced in 6 patients and increased in 8 patients; there was no mean change. The decrease in 5‐HIAA level in CSF was correlated to the uptake inhibition of 5‐HT but there was no corresponding relationship between NE uptake and HMPG levels. The changes in HVA levels were also correlated to the uptake of 5‐HT despite the absence of a unidirectional change of this metabolite.