Influences of housing conditions and ethanol intake on binding characteristics of D 2, 5-HT 1A, and benzodiazepine receptors of rats

Abstract

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 ([ 3H]spiperone), hippocampal serotonergic 5-HT 1A ([ 3H]8-OH-DPAT), and cortical benzodiazepine ([ 3H]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 had no effect on S-HT 1A 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 [ 3H]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.