Dopamine D2 Receptor Availability and Amphetamine-Induced Dopamine Release in Unipolar Depression

Background: Reduced dopaminergic transmission has been implicated in the pathophysiology of major depression. The aim of the present study was to measure striatal D-2 receptor availability and amphetamine-induced dopamine release in nonpsychotic, unmedicated, unipolar patients during an episode of major depression.Methods: The striatal equilibrium specific to nonspecific partition coefficient (V-3") of the D-2 receptor antagonist [I-123]IBZM was measured with single photon emission computerized tomography before and after amphetamine administration in 9 depressed subjects and 10 matched healthy control subjects.Results: No significant differences were observed in preamphetamine D-2 receptor availability between depressed patients (0.73 +/- 0.08) and control subjects (0.78 +/- 0.10, p =.23). Amphetamine-induced reduction in [I-123]IBZM 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 improvement in symptomatology in depressed patients, but this improvement did not correlate with [I-123]IBZM DeltaV(3)"Conclusions: This study did not replicate previously reported alterations in striatal D-2 receptor density in depressed patients and suggests that stimulant-induced dopamine release is not altered in major depression. Biol Psychiatry 2001;50:313-322 (C) 2001 Society of Biological Psychiatry.