Dopaminergic abnormalities in amygdaloid nuclei in major depression: a postmortem study

Background A deficiency of mesolimbic dopamine (DA) is a leading candidate for the etiology of certain symptoms of depression (e.g., anhedonia and loss of motivation). Here we show amounts of dopaminergic proteins in the amygdala, a key brain structure involved in the integration of emotions and stress, in subjects with major depression and in psychiatrically normal control subjects. Methods The specific binding of [125I]RTI 55 to the DA transporter, [3H]SCH 23390 to the D1 receptor and [125I]epidepride to D2/D3 receptors were measured in the right amygdaloid complex in postmortem brains from 11 subjects with major depression and 11 matched control subjects. Results The binding of [125I]RTI 55 to DA transporter was significantly lower in the basal and central amygdaloid nuclei, whereas the binding of [125I]epidepride to D2/D3 receptors was significantly higher in the basal, central, and lateral amygdaloid nuclei in major depression compared with control subjects. No difference in the binding of [3H]SCH 23390 to D1 receptors was observed. Conclusions Given that DA depletion in rats can induce a reduction in the DA transporter and an upregulation of D2/D3 receptors, our data are consistent with the hypothesis that major depression is associated with a deficiency of mesolimbic DA.