The authors report cerebrospinal fluid (CSF) concentrations of five
monoamine metabolites before and after probenecid administration in normal
subjects and patients with depression and schizophrenia. No differences
were found in baseline metabolite concentrations among the three groups.
CSF metabolite and CSF probenecid concentrations were significantly
correlated in depressed patients for all metabolites, and there was
decreased postprobenecid accumulation of homovanillic acid in the CSF of
depressed patients compared with schizophrenic patients and with normal
subjects. The authors propose a method for correcting for probenecid
concentrations. Data from normal subjects should be of value for other
investigators using the probenecid technique.