SUSTAINED WITHDRAWAL ALLOWS NORMALIZATION OF IN-VIVO [C-11] N-METHYLSPIPERONE DOPAMINE D-2 RECEPTOR-BINDING AFTER CHRONIC BINGE COCAINE - APOSITRON-EMISSION-TOMOGRAPHY STUDY IN RATS

In our previous positron emission tomography studies striatal binding for both [C-11]SCH23390 and [C-11]N-methylspiperone (NMSP) were decrea sed in the rat brain on the last day of chronic (14 days) binge cocain e administration. We have found that [C-11]SCH23390 binding to dopamin e D-1 receptors returns to saline control levels within ten days withd rawal from chronic binge cocaine and remains at control levels after 2 1 days withdrawal. An 18% decrease in [C-11]NMSP binding to dopamine D -2 receptors was observed after ten days withdrawal. However, importan tly, after 21 days withdrawal [C-11]NMSP binding was at saline control levels. Changes of in vivo [C-11]NMSP binding required a longer absti nence period for normalization than [C-11]SCH23390 binding. The appare nt recovery of dopamine D-2 receptors after prolonged abstinence from chronic cocaine and the different rates of normalization for dopamine D-1 versus D-2 receptors may be critical information for development o f pharmacotherapies for cocaine dependent patients. (C) 1998 American College of Neuropsychopharmacology. Published by Elsevier Science Inc.