STRIATAL D-2 DOPAMINE-RECEPTOR BINDING CHARACTERISTICS IN-VIVO IN PATIENTS WITH ALCOHOL DEPENDENCE

Striatal D-2 dopamine receptor characteristics of nine male patients with alcohol dependence abstinent for 1-68 weeks and eight healthy male volunteers were studied in vivo with positron emission tomography. The selective D-2 receptor ligand [C-11]raclopride and equilibrium model was used for D-2 receptor density (B-max) and affinity (K-d) measurements. A trend for a decreased striatal D-2 receptor density and for reduced D-2 receptor affinity was observed in patients with alcohol dependence. These parameters were not statistically significantly different between alcoholics and controls, but the ratio between D-2 receptor density and affinity (B-max/K-d or the striatum/cerebellum ratio from the high specific activity scan) was highly significantly lower in alcoholics than that of controls. In conclusion, the low D-2 dopamine receptor B-max/K-d ratio (striatum/cerebellum ratio) indicates that specific aspects of striatal [C-11]raclopride binding in vivo are deviant in alcoholics compared to controls. The result is compatible with a reduced avidity of striatal dopamine D-2 receptors in alcoholics, which is in line with the idea that D-2 dopaminergic mechanisms are involved in the biology of alcohol dependence in man.