The prolactin response to sulpiride in major depression: The role of the D2 receptor in depression

Multiple lines of investigations have implicated the role of the dopaminergic system in depression. The aim of the study was to characterise the Dopamine D₂ receptor sensitivity status in depressed patients versus controls by means of a novel neuro-endocrine challenge test, the prolactin response to sulpiride. In this intervention, ten patients and ten age matched male volunteers were studied. The patients were diagnosed according to DSM-IV criteria, and Montgomery Asberg and Zung scales were done. There was no significant difference in baseline levels of prolactin between the depressed and control groups. Significantly higher prolactin levels after sulpiride challenge were however found in depressed patients than controls at all time points after sulpiride administration. This neuroendocrine challenge paradigm suggests that the prolactin response to sulpiride, a D₂ receptor antagonist, is enhanced in depression, which suggests that this receptor might be supersensitive in depression compared to controls. This adds to the data implicating the dopaminergic system in the pathophysiology of depression, and suggests that dopaminergic mechanisms might be a target of therapeutic interest.