Multiple sources of evidence support a role for diminished dopaminergic neurotrans-mission
in major depression. The physiological alterations underlying reduced dopa-mine (DA)
signaling could result from either diminished DA release from presynaptic neurons or
impaired signal transduction, either due to changes in receptor number or function and/or
altered intracellular signal processing. There are data supporting each of these
mechanisms, although interpretation of previous research is confounded by issues around …