PET neuroimaging of clomipramine challenge in humans: focus on the thalamus

PET neuroimaging of serotonin responsivity relied previously mainly on fenf luramine, but that drug has been withdrawn from the market. Therefore, we d etermined whether clomipramine, which stimulates serotonergic mechanisms by inhibiting serotonin reuptake, has reliable effects in the healthy human b rain as measured by [O-15]H2O PET. The clomipramine challenge markedly redu ced the relative rate of blood flow in the selected region of interest, nam ely the dorsomedial nucleus of the thalamus, a limbic region rich in seroto nin uptake sites. These findings show similarities between effects of fenfl uramine and clomipramine in the healthy human brain, and support the use of the clomipramine challenge in conjunction with PET for studying cerebral s erotonergic mechanisms. (C) 2001 Elsevier Science B.V. All rights reserved.