Serotonin-2 receptors in the CNS of alcohol-preferring and -nonpreferring rats

The densities of serotonin-2 (5-HT2) receptors, labelled with [3H]ketanserin (Ket), were examined in the CNS of alcohol-naive, adult, male alcohol-preferring (P) and -nonpreferring (NP) rats using quantitative autoradiography. The densities of binding sites labelled with 2.0 nM [3H]Ket were 15-25% lower (p < 0.05) in layer IV of the medial prefrontal, frontal, cingulate, parietal, and temporal cortices of the P line compared with the NP line. [3H]Ket binding in the P rats was also 40-50% lower (p < 0.05) in the medial and lateral nucleus accumbens, olfactory tubercle, and caudate-putamen, and 20% lower (p < 0.05) in the claustrum, compared with the NP line. No differences in 2.0 nM [3H]Ket binding were observed between the lines in the piriform cortex, hypothalamus, amygdala, hippocampus, ventral tegmental area, substantia nigra, central gray, and interpenduncular nucleus. Scatchard analysis of [3H]Ket binding (0.5-0.6 nM, determined in layer IV of the frontal and parietal cortex and in the lateral nucleus accumbens, indicated lower Bmax values without a change in Kd for the P compared to the NP rats. The results of this study indicate that there are fewer 5-HT2 receptors in certain CNS regions of the P relative to the NP rats.