Dopamine D1 Receptors in Cocaine Dependence Measured with PET and the Choice to Self-Administer Cocaine

Abstract

ObjectiveThe goal of this study was to determine D1 receptor availability in human cocaine dependent (CD) subjects and matched healthy controls (HC). In addition, the cocaine dependent subjects performed cocaine self-administration sessions in order to explore the association between D1 receptor availability and cocaine seeking behavior.Methods25 cocaine dependent subjects (40 ±4 yrs, 19M/6 F) and 23 matched healthy controls (38 ±4 yrs, 19M/4F) were scanned with PET and the radiotracer [11C]NNC 112. During the cocaine self-administration sessions, cocaine dependent volunteers were given the choice to self-administer cocaine (0, 6, and 12 mg) or to receive a monetary voucher worth $5. D1 receptor availability was measured in the limbic, associative and sensori-motor striatum in addition to cortical brain regions.ResultsNo difference in D1 receptor availability was seen between the two groups. A negative association was seen between D1 receptor BPND in the limbic striatum and the choice for the 6 mg dose of cocaine (r = - 0.47, p = 0.02, corrected for age).ConclusionsThese results do not support the hypothesis that cocaine dependence is associated with a reduction in D1 receptor availability in the striatum. However, within the cocaine-dependent subjects, low D1 receptor availability in the ventral striatum was associated with the choice to self-administer cocaine, suggesting that low D1 receptor availability may be associated with an increased risk of relapse in cocaine dependence.