Serotonergic and adrenergic receptors in alcohol-preferring and non-preferring rats

Serotonergic and adrenergic receptors in brain areas of the alcohol-preferring P and alcohol-nonpreferring NP rats were compared by radioligand-binding assays. Binding of 3H-serotonin (3H-5HT) to 5HT-1 receptors in membranes of cerebral cortex and hippocampus was significantly higher in density (B max values) and affinity (Kd values) in the P than in the NP rats, whereas B max values in membranes from the brain stem of the P rats were lower than those of the NP rats. No significant difference between the P and NP lines was observed when the binding of 3H-ketanserin to 5HT-2 receptors and of 3H-WB4101, 3H-clonidine and 3H-dihydoalprenolol to alpha-1, alpha-2 and beta-adrenergic receptors was compared. The increase of 3H-5HT binding probably indicates up-regulation or supersensitivity of 5HT-1 receptors as a compensatory mechanism to the lower levels of 5HT in brain areas of the P rats (Murphy, et al., 1982).