Selective antidepressants and cerebrospinal fluid. Lack of specificity on norepinephrine and serotonin metabolites

Cerebrospinal fluid concentrations of the norepinephrine metabolite, 3-methoxy-4-hydroxyphenylglycol (MHPG), the serotonin metabolite, 5-hydroxyindoleacetic acid (5-HIAA), and the dopamine metabolite, homovanillic acid, were measured in depressed patients before and after treatment with three putatively specific antidepressants. The expected specificity of action on these three neurotransmitter metabolites was not observed. Desipramine hydrochloride, a norepinephrine uptake inhibitor, reduced 5-HIAA as well as MHPG concentrations; zimeldine hydrochloride, a serotonin uptake inhibitor, reduced MHPG as well as 5-HIAA concentrations; and clorgyline, a selective monoamine oxidase type A inhibitor, which might be predicted to most affect 5-HIAA, dramatically reduced MHPG, moderately reduced homovanillic acid, and only modestly reduced 5-HIAA concentrations.