INFLUENCES OF HOUSING CONDITIONS AND ETHANOL INTAKE ON BINDING CHARACTERISTICS OF D-2, 5-HT1A, AND BENZODIAZEPINE RECEPTORS OF RATS

The effects of different housing conditions and ethanol treatment (6 vol % in the drinking water) on the in vitro binding characteristics of striatal dopaminergic D-2 ( H-3 spiperone), hippocampal serotonergic 5-HT1A ( H-3 8-OH-DPAT), and cortical benzodiazepine ( H-3 flunitrazepam) receptors have been examined. Social deprivation due to contact caging, short- (1 day) and long-term isolation (5 weeks) yielded a significant decrease of striatal D-2 receptor density with the greatest decrease after long-term isolation (-21% B-max) without changes of K-d in comparison to group animals. The effect of ethanol on striatal D-2 receptor density depended on the housing conditions. Whereas ethanol treatment reduced receptor density of group animals (down to 88%), chronic exposure to ethanol under long-term isolation elicited no significant alteration of D-2 receptor density compared with group animals. Different housing and ethanol treatment bad no effect on 5-HT1A receptor affinity and density. Alterations of benzodiazepine receptor density were not found, but social deprivation as well as ethanol treatment of group animals caused an increased affinity of H-3 flunitrazepam (reduced K-d value). These results indicate that different housing conditions of adult rats evoked significant alterations in D-2 and benzodiazepine receptor binding assays, which were modified by ethanol treatment in the case of striatal D-2 receptor density.