EVIDENCE FOR REDUCED DOPAMINE D2 RECEPTOR SENSITIVITY IN POSTWITHDRAWAL ALCOHOLICS

Dopamine D2 receptor sensitivity was assessed in the post-withdrawal p eriod in alcoholics. Growth hormone (GH) responses to dopamine D2 agon ist bromocriptine were measured in eight DSM-III-R alcohol-dependent s ubjects who were 2 weeks or more postalcohol withdrawal. Their respons es were compared with eight nonalcoholic controls. After an overnight fast, each subject received 1.25 mg of bromocriptine orally, and seria l samples of GH were taken over a 3-hr period. There was a significant ly blunted delta GH response (mean +/- SE) in the alcoholic group, 2.3 mU/liter (+/- 1.4) relative to controls, 7.7 mU/liter(+/- 1.2) (t = 2 .96, df = 14, p = 0.01), There was a significantly blunted peak GH res ponse (mean +/- SE) in the alcoholic group, 5.36 mU/liter (+/- 2.1) re lative to controls, 9.04 mU/liter (+/- 5.0). This difference also reac hed statistical significance (t = 2.32, df = 14, p = 0.035). A repeate d-measures ANOVA yielded a significant within-subjects effect of time [F(4,54) = 4.08, p = 0.0057], a significant with-in-subjects effect of group [F(1,14) = 5.6, p = 0.0329], and an almost significant group x time interaction [F(4,54) = 2.45, p = 0.056]. This result implies a re lative dopamine D2 receptor subsensitivity in alcoholics in the postwi thdrawal period.