Amphetamine-Induced Displacement of [18F] Fallypride in Striatum and Extrastriatal Regions in Humans

Abstract

This study examined D-amphetamine (D-AMPH)-induced displacements of [18F] fallypride in striatal and extrastriatal regions and the correlations of these displacements with cognition, affect, and sensation-seeking behavior. In all, 14 normal subjects, six females and eight males (ages 21-32, mean age 25.9 years), underwent positron emission tomography (PET) with [18F]fallypride before and 3 h after a 0.43 mg/kg oral dose of D-AMPH. Levels of dopamine (DA) D2 receptor density were calculated with the reference region method of Lammerstma. Percent displacements in striatal and extrastriatal regions were calculated for the caudate, putamen, ventral striatum, medial thalamus, amygdala, substantia nigra, and temporal cortex. Correlations of changes in cognition, affect, and sensation seeking with parametric images of D-AMPH-induced DA release were computed. Significant displacements were seen in the caudate, putamen, ventral striatum substantia nigra, and temporal cortex with a trend level change in the amygdala. Greatest displacements were seen in striatal subdivisions-5.6% in caudate, 11.2% in putamen, 7.2% in ventral striatum, and 6.6% in substantia nigra. Lesser decrements were seen in amygdala-4.4%, temporal cortex-3.7%, and thalamus-2.8%. Significant clusters of correlations of regional DA release with cognition and sensation-seeking behavior were observed. The current study demonstrates that [18F]fallypride PET studies using oral D-AMPH (0.43 mg/kg) can be used to study D-AMPH-induced DA release in the striatal and extrastriatal regions in humans, and their relationship with cognition and sensation-seeking behavior.