Regional central nervous system densities of delta-opioid receptors in alcohol-preferring P, alcohol-nonpreferring NP, and unselected Wistar rats
The densities of delta-opioid receptors in the central nervous system of alcohol-naive, adult, male, alcohol-preferring P, alcohol-nonpreferring NP, and Wistar rats were examined with the use of quantitative autoradiography. Slides with coronal 20-μm sections through the regions of interest were incubated in 5 nM [3H]-[D-Pen2,D-Pen5]enkephalin (DPDPE) to label delta1-opioid receptor sites. Nonspecific binding was determined in the presence of 10 μM naloxone. Significant differences between the P and the NP rat lines were found in numerous cortical regions, the basolateral amygdala, and the posterior hippocampus, with 10%-20% lower [3H]-DPDPE binding found in the P line. In most regions examined, binding levels in the Wistar rats were intermediate between those of the P and the NP rats. Significantly lower [3H]-DPDPE binding levels in the P rat may indicate fewer delta1-opioid receptors or decreased binding affinity. The lower binding in certain limbic regions, such as the basolateral amygdala and posterior hippocampus, as well as cortical differences in the P rat may be associated with the divergent alcohol drinking behaviors found between the P and the NP lines. Copyright © 2001 Elsevier Science Inc.
Strother, WN; Chernet, EJ; Lumeng, L; Li, TK; McBride, WJ
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