Dopamine D-2 receptor availability and amphetamine-induced dopamine release in unipolar depression

Background: Reduced dopaminergic transmission has been implicated in the pa thophysiology of major depression. The aim of the present study was to meas ure striatal D-2 receptor availability and amphetamine-induced dopamine rel ease in nonpsychotic, unmedicated, unipolar patients during an episode of m ajor depression. Methods: The striatal equilibrium specific to nonspecific partition coeffic ient (V-3") of the D-2 receptor antagonist [I-123]IBZM was measured with si ngle photon emission computerized tomography before and after amphetamine a dministration in 9 depressed subjects and 10 matched healthy control subjec ts. Results: No significant differences were observed in preamphetamine D-2 rec eptor availability between depressed patients (0.73 +/- 0.08) and control s ubjects (0.78 +/- 0.10, p =.23). Amphetamine-induced reduction in [I-123]IB ZM V-3" (DeltaV(3)") was similar in depressed patients (-9.8 +/- 5.5%) and control subjects (-7.8 +/- 2.5%, p =.32). Amphetamine induced a transient i mprovement in symptomatology in depressed patients, but this improvement di d not correlate with [I-123]IBZM DeltaV(3)" Conclusions: This study did not replicate previously reported alterations i n striatal D-2 receptor density in depressed patients and suggests that sti mulant-induced dopamine release is not altered in major depression. Biol Ps ychiatry 2001;50:313-322 (C) 2001 Society of Biological Psychiatry.