Regional serotonin1A receptors in the CNS of alcohol-preferring and -nonpreferring rats.

The densities of serotonin1A (5-HT1A) receptors, labeled with [3H]8-hydroxy-2-(di-n-propylamino) tetralin (8-OH-DPAT), were examined in the CNS of alcohol-naive adult male alcohol-preferring (P) and -nonpreferring (NP) rats using quantitative autoradiography. The densities of sites labeled with 2 nM [3H]8-OH-DPAT were a) 20-30% higher in the medial prefrontal, frontal (layers 1, 2, and layers 3-6), parietal (layers 3-6), and cingulate cortex; b) 35-40% higher in the retrosplenial, occipital (all layers), temporal (all layers) cortex; and c) 15% higher in the entorhinal cortex of the P compared with the NP rat. Within the hippocampus, significant differences between the rat lines were observed only in the posterior portion where the densities of [3H]8-OH-DPAT labeled sites were a) 10-15% higher in the dorsal dentate gyrus, dorsal CA1, and dorsal CA3 regions; and b) 15-25% higher in the anterior ventral hippocampal area and ventral dentate gyrus of the P relative to the NP line. In contrast to the above results, the densities of [3H]8-OH-DPAT labeled sites were 15-20% lower in the dorsal, paradorsal, and median raphe nuclei of the P compared with the NP rat. No differences in [3H]8-OH-DPAT binding between the rat lines were found in several basal ganglia, limbic, and brain stem regions. The data indicate that there are greater numbers of postsynaptic 5-HT1A receptors in certain parts of the cerebral cortex and hippocampus of the P compared with the NP rat.(ABSTRACT TRUNCATED AT 250 WORDS)