Concentration gradients of monoamine metabolites in human cerebrospinal fluid

The monamine metabolites 5-hydroxyindoleacetic acid (5-HIAA), homovanillic acid (HVA), vanillylmandelic acid (VMA), and 4-hydroxy-3-methoxyphenylglycol (HMPG) were analysed in CSF from different regions of the CSF system to study the caudocranial concentration gradient of the metabolites. Four consecutive 10 ml fractions of CSF were withdrawn in 17 patients during the course of four minutes. The CSF pressure was monitored through a lumbar cannula because of suspected adult hydrocephalus. A pronounced gradient of the HVA concentration was found with a ratio between the last and the first fraction of 1,7. 5-HIAA showed a slight increase while HMPG and VMA showed no increase at higher levels of the CSF system. The results suggest that lumbar HVA reflects dopaminergic activity in the brain, whereas lumbar 5-HIAA and HMPG/VMA reflect the activity of 5-hydroxytryptamine and noradrenaline secreting neurones in both the brain and the spinal cord.