Regional CNS densities of monoamine receptors in alcohol-naive alcohol-preferring P and -nonpreferring NP rats

The densities of subtypes of serotonin (5-HT) and dopamine (DA) receptors were determined in the CNS of alcohol-naive alcohol-preferring P and -nonpreferring NP lines of rats. Autoradiography studies were undertaken to measure the densities of 5-KT1B sites labelled with 100 pM [I-125](-)-iodocyanopindolol, 5-HT3 sites labelled with 2 nM [H-3]LY 278584, and D-1 sites labelled with 1 nM [H-3]SCH 23390. Membrane binding, using tissue combined from the olfactory bulb, olfactory tubercle, and nucleus accumbens, was carried out to determine K-d and B-max values for the binding of 0.25-8.0 nM [H-3]7-OH DPAT to D-3 sites. Among the 48 regions measured for differences in 5-HT1B recognition sites, statistically significant differences (p < 0.05) were found only in the cingulate and retrosplenial cortices, in the lateral and medial septum, and in the lateral nucleus of the amygdala, with lower values being found in the P than the NP line. There were no significant differences in the: regional CNS densities of D-1 or 5-HT, sites between the P and NP lines. There were also no differences between the rat lines in the K-d or B-max values for [H-3]7-OH DPAT binding to D-3 sites. The lower densities of 5-HT1B sites in the CNS of the P compared to the NP rats may be a result of reduced numbers of 5-HT1B presynaptic autoreceptors as well as postsynaptic receptors in the P line. The observation that there are no differences in the amount of radioligand binding to D-1, 5-HT3, and D-3 sites between the P and NP lines suggests that the disparate alcohol drinking behaviors of these two lines is not associated with an innate alteration in the densities of these receptor subtypes. (C) 1997 Elsevier Science Inc.