Binding of serotonergic ligands to brain membranes of alcohol-preferring AA and alcohol-avoiding ANA rats

Abstract The alcohol-preferring AA rats have higher concentration of 5-hydroxytryptamine (5-HT) in the brain than the alcohol-avoiding ANA rats. In the present study, the 5-HT 1 , 5-HT 2 , and 5-HT 3 receptors were studied with [ 3 H]5-HT, [ 3 H]ketanserin, and [ 3 H]LY278584, respectively, in membrane homogenates from different brain regions of both rat lines using in vitro binding assays. No differences in the 5-HT 1 and 5-HT 2 receptor binding in the brainstem, hippocampus, frontal cortex, and hypothalamus or in the 5-HT 3 receptor binding in the nucleus accumbens, amygdala, hippocampus, and frontal cortex were observed between the ethanol-naive animals of the rat lines. In rats given the opportunity to voluntarily consume alcohol, there was a tendency to increase 5-HT 1 binding in the ANA rats, which tendency was, however, also found in their ethanol-naive controls subjected to the same handling and behavioral tests as the ethanol-experienced animals. The results do not, however, indicate that any genetic modifications of the 5-HT receptor-binding sites have occurred in the process of the selective breeding of AA and ANA rats for alcohol preference and avoidance, respectively.