Alteration of dopamine transport and dopamine D(2) receptor binding in the brain induced by early and late consequences of global ischaemia caused by cardiac arrest in the rat.

Abstract

This study was designed to determine the effects of global cerebral ischaemia caused by temporary cardiac arrest and the early and late consequences of this ischaemia on dopamine transport and dopamine D(2) receptor binding in rat brain. The effects of 10 min of global ischaemia were measured immediately and after 1 h and 7 days post-resuscitation. A decrease of dopamine uptake in the rats by synaptosomes was noted immediately following global ischaemia and 1 h after resuscitation. However, at 7 days post-resuscitation, the dopamine uptake returned to control values. Reversibility of the changes in the synaptosomal dopamine uptake is undoubtedly a favourable sign. Global ischaemia and reperfusion after 1 h or 7 days did not show altered rates of dopamine release but did affect the dopamine D(2) receptor. An observed increase of receptor affinity may be an adaptive response to the reduction in binding capacity. The reduction of visible D(2) receptor binding sites in the early post-resuscitation phase, which was extended to the period of 7 days after resuscitation without recovery, is probably associated with neuronal necrotic damage.