KAPPA(1) RECEPTOR MESSENGER-RNA DISTRIBUTION IN THE RAT CNS - COMPARISON TO KAPPA-RECEPTOR-BINDING AND PRODYNORPHIN MESSENGER-RNA

Three opioid receptor types have been identified in the CNS and periph ery that are referred to as mu, delta, and kappa. The present study ex amines the mRNA distribution of the kappa(1) receptor in the rat brain and compares it to the distribution of kappa receptor-binding sites a nd prodynorphin mRNA using a combination of in situ hybridization and receptor autoradiographic techniques. kappa(1) receptor mRNA was local ized with a cRNA probe generated with a BamHI-HindIII cDNA fragment of the rat kappa(1) receptor and corresponds to the last 45 bp of the pr otein coding region and 728 nucleotides of the 3' untranslated region. Prodynorphin mRNA was localized with a cRNA probe corresponding to a 733-bp BamHI-HincII fragment of prodynorphin. kappa receptor-binding s ites were labeled in one of two ways: [H-3]U69,593 or [3H]bremazocine in the presence of a 300-fold excess of DAMGO and DPDPE. A high degree of correspondence between the kappa(1) receptor mRNA and kappa recept or binding was observed in several brain regions, including the endopi riform nucleus, claustrum, nucleus accumbens, olfactory tubercle, bed nucleus of the stria terminalis, medial preoptic area, paraventricular , supraoptic, suprachiasmatic, dorsomedial and ventromedial hypothalam ic nuclei, basolateral, medial and cortical amygdaloid nuclei, midline thalamic nuclei, periaqueductal grey, parabrachial nucleus, locus coe ruleus, and the nucleus of the solitary tract. Differences in the loca lization of kappa(1) receptor mRNA and binding and the relationship be tween the distribution of kappa(1) receptor and prodynorphin mRNAs are discussed. (C) 1994 Academic Press, Inc.