Monoamine precursors, transmitters and metabolites in cerebrospinal fluid: a prospective study in healthy male subjects.

In order to elucidate methodological aspects of CSF investigations, 14 healthy male subjects were lumbar-punctured at the L4-5 level following a standardised procedure. CSF concentrations of precursors, transmitters and transmitter metabolites were used as dependent variables, while age, height, body weight, atmospheric pressure and some other factors served as independent variables. 5-HIAA and HVA (but not HMPG) have pronounced concentration gradients. We also found CSF gradients for the precursors tryptophan and tyrosine, as well as for serotonin, dopamine and the dopamine metabolite DOPAC. Dopamine and atmospheric pressure showed a positive intercorrelation. Age correlated curvilinearly (convex upward) with tryptophan but showed a negatively directed linear correlation with serotonin. Serotonin and 5-HIAA showed no intercorrelation. Our results suggest an age-dependent disposition of tryptophan in the CSF. The absence of a correlation between serotonin and 5-HIAA might be inconsistent with the notion that 5-HIAA is a marker of central serotonin turnover. The comparatively high body weight of our volunteers might explain the lack of a gradient for HMPG.