Characterization of Y 1, Y 2 and Y 5 subtypes of the neuropeptide Y (NPY) receptor in rabbit kidney : Sensitivity of ligand binding to guanine nucleotides and phospholipase C inhibitors

Abstract

The binding of two peptide YY/neuropeptide Y analogues selective for major subtypes of neuropeptide Y (NPY) receptors was compared in particulates from rabbit kidney cortex employing modulators of activity of G-proteins, phospholipase enzymes, and ion channels. The binding of (Leu 31,Pro 34)human peptide YY resembled the patterns observed previously for the brain tissue Y 1 receptor, exhibiting a high sensitivity to monovalent cations, disulfide disruptors, guanosine polyphosphates and phospholipase C inhibitors. However, this binding was bimodal in response to human pancreatic polypeptide and to peptides selective for the Y 2 subtype of the NPY receptor, displaying a large component pharmacologically similar to the brain Y 5 receptor. This kidney Y 5-like binding largely shared the sensitivity to monovalent cations, guanine nucleotides and phospholipase C inhibitors found for either the kidney or the brain Y 1 receptor, and also was activated by Ca 2+ ion. Both Y 1- and Y 5-like binding in the kidney displayed a uniformly low reactivity to a nonpeptidic Y 1 antagonist, BIBP-3226, and to a receptor peptide mimetic, mastoparan analogue MAS-7. The kidney Y 2 binding shared the low sensitivity to ionic environment observed for the brain Y 2 subtype, and was only partially sensitive to guanine nucleotides or to MAS-7. The Y 2 liganding had a sensitivity to phospholipase C inhibitors similar to the Y 1/Y 5 binding. This reactivity was retained in the fraction of the Y 2 receptor persisting detergent solubilization in a high-affinity form, which, however, was activated rather than inhibited by G-protein agonists.