Dopamine D(1) receptors in cocaine dependence measured with PET and the choice to self-administer cocaine

OBJECTIVE: The goal of this study was to determine D(1) 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 D(1) receptor availability and cocaine seeking behavior. METHODS: 25 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 [(11)C]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. D(1) receptor availability was measured in the limbic, associative and sensori-motor striatum in addition to cortical brain regions. RESULTS: No difference in D(1) receptor availability was seen between the two groups. A negative association was seen between D1 receptor BP(ND) in the limbic striatum and the choice for the 6 mg dose of cocaine (r = - 0.47, p = 0.02, corrected for age). CONCLUSIONS: These results do not support the hypothesis that cocaine dependence is associated with a reduction in D(1) receptor availability in the striatum. However, within the cocaine-dependent subjects, low D(1) receptor availability in the ventral striatum was associated with the choice to self-administer cocaine, suggesting that low D(1) receptor availability may be associated with an increased risk of relapse in cocaine dependence.