The response to sulpiride in major depression before and after cognitive behavioural therapy: D2 receptor function

Previous studies have suggested that antidepressant treatment of depression may potentiate dopamine transmission through increased sensitivity of postsynaptic D2 receptors.

D2 receptor function was assessed in 24 patients with major depression before and 16 patients after 16 weeks of treatment with cognitive behavioural therapy (CBT) using a challenge with a selective D2 antagonist, sulpiride. Four hundred milligrams of sulpiride was administered orally on two test days and response was measured by the change in prolactin levels and changes in self-rating scale measures of mood, anxiety and pleasure.

The prolactin response to sulpiride (as measured by the maximum prolactin level) was significantly increased after CBT (z = -2.792, p = 0.005). Sulpiride resulted in an improvement on mood ratings on both test days, but after CBT, this effect was significantly diminished as measured by the Profile of Mood States score (t = -2.27, p = 0.038).

After 16 weeks of CBT, we detected an enhanced prolactin response to sulpiride, suggesting an increased sensitivity of D2 receptor functioning.