Assuntos
Proteínas de Transporte/metabolismo , Corpo Estriado/metabolismo , Transtorno Depressivo Maior/metabolismo , Glicoproteínas de Membrana , Proteínas de Membrana Transportadoras , Proteínas do Tecido Nervoso , Transtornos da Personalidade/metabolismo , Adulto , Corpo Estriado/diagnóstico por imagem , Transtorno Depressivo Maior/diagnóstico por imagem , Proteínas da Membrana Plasmática de Transporte de Dopamina , Feminino , Humanos , Masculino , Transtornos da Personalidade/diagnóstico por imagem , Tomografia Computadorizada de Emissão de Fóton ÚnicoRESUMO
RATIONALE: There are no previous data available regarding [123I]beta-CIT binding to the dopamine transporter sites in the basal ganglia in depressed patients. OBJECTIVE: The present study tested the hypothesis that the brain DAT density in depressed patients is lower than that in matched healthy controls. METHODS: Fifteen drug-naive outpatients with major depression and 18 healthy controls were investigated using single photon emission computerized tomography (SPECT) with a high-affinity dopamine transporter specific radioligand. 123I-labeled beta-CIT (2beta-carbomethoxy-3beta-(4-iodophenyl-tropane). RESULTS: We found a significantly higher [123I]beta-CIT uptake in both sides of the basal ganglia in patients with major depression than in the controls (Mann-Whitney U-test, P = 0.002 on the right and P = 0.003 on the left). CONCLUSIONS: The radioligand uptake reflecting the DAT density was significantly higher among the patients than in the controls. This finding is unexpected, since it is generally believed that monoaminergic neurotransmission is lower in depression, and therefore it could be assumed that a reduction in dopamine transmission would lead to secondary down-regulation of DAT density. However, it is possible that up-regulation of the DAT may be the primary alteration, which leads to lower intrasynaptic dopamine concentration and to lower dopamine neural transmission.