CHARACTERIZATION AND MOLECULAR-CLONING OF VASCULAR NEUROPEPTIDE-Y RECEPTOR SUBTYPES IN PIG AND DOG

Cloning with subsequent in vitro and in vivo characterization of vascu lar neuropeptide Y (NPY) receptor subtypes in porcine and canine perip heral tissues was performed. RT-PCR with Y-1 and Y-2 receptor-specific primers, indicated expression of Y-2 receptors in both kidney and spl een of dog and pig, and expression of Y-1 receptors in pig spleen. In pig kidney, expression of Y-1 receptor mRNA was located to intrarenal arteries, as demonstrated with in situ hybridization using human probe s. The cloned and sequenced canine Y-1, porcine Y-1 and Y-2 receptors revealed high homologies to previously characterized mammalian NPY rec eptors. Membrane and autoradiographic receptor binding studies showed specific high-affinity binding sites for the purported Y-1-selective r adioligands I-125-[Leu(31)Pro(34)]peptide YY (PYY) and H-3-BIBP 3226 i n dog spleen, and for the putative Y-2-selective I-125-PYY(3-36) in do g and pig spleen. In the pig in vivo, [Leu(31)Pro(34)]PYY, administere d i.v., evoked vasoconstriction in spleen and kidney, actions that wer e potently inhibited by the non-peptide Y-1 receptor antagonist SR 120 107A. In contrast, PYY(3-36) evoked vasoconstriction only in spleen an d this effect was not influenced by SR 120107A. NPY evoked renal and s plenic vasoconstriction in the dog in vivo, vascular responses that we re inhibited by both BIBP 3226 and SR 120107A. Furthermore, the Y-1 re ceptor agonist [Leu(31)Pro(34)]NPY also caused vasoconstriction in dog kidney and spleen, whereas the putative Y-2 agonist N-acetyl[Leu(28)L eu(31)]NPY(24-36) evoked no such vascular responses. It is concluded t hat the pig spleen is likely to contain Y-1 and Y-2 receptors, both in volved in splenic vasoconstriction. In contrast, the Y-1 receptor seem s to be the sole vascular NPY receptor subtype in pig kidney. Moreover , Y-1 receptors predominate in dog spleen and kidney. Furthermore, the cloned canine Y-1 receptor and the porcine Y-1 and Y-2 receptors show great homologies to, and possess ligand requirement profiles in accor dance with, the human forms. (C) 1998 Elsevier Science B.V.