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-HT(IB) sites labelled with 100 pM [125I](- )-iodocyanopindolol, 5-HT3 sites labelled with 2 nM [3H]LY 278584, and D1 sites labelled with 1 nM [3H]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 [3H]7-OH DPAT to D3 sites. Among the 48 regions measured for differences in 5-HT(IB) 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 D1 or 5-HT3 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 [3H]7-OH DPAT binding to D3 sites. The lower densities of 5-HT(IB) sites in the CNS of the P compared to the NP rats may be a result of reduced numbers of 5-HT(IB) 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 D1, 5-HT3, and D3 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.
McBride, WJ; Chernet, E; Russell, RN; Wong, DT; Guan, XM; Lumeng, L; Li, TK
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