IMAGING ENDOGENOUS DOPAMINE COMPETITION WITH [C-11] RACLOPRIDE IN THEHUMAN BRAIN

This study images dopamine release in response to a neurochemically sp ecific challenge with the psychostimulant drug methylphenidate. Change s in synaptic dopamine induced by methylphenidate were evaluated with positron emission tomography and [C-11]raclopride, a D2 receptor radio ligand that is sensitive to endogenous dopamine. Methylphenidate signi ficantly decreased striatal [C-11]raclopride binding. The decrease was variable and was negatively correlated with age. Mood and anxiety at baseline, were also correlated with methylphenidate-induced DA changes . This strategy provides a tool to investigate the responsiveness of t he dopamine system in the normal and diseased human brain and to inves tigate the neurochemical correlates of behavior. (C) 1994 Wiley-Liss, Inc.