Development of receptor antagonists to neuropeptide Y,galanin and pancreastatin

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The principal aim of this proposal is to develop receptor antagonists to neuropeptide Y (NPY), galanin and pancreastatin (PST) as drugs against diabetes, hypertension and endocrine abnormalities. Toward this goal, we first set up a new laboratory which is capable of carrying out cell culture experiments, peptide synthesis and structural determination, and then, we carried out synthetic studies for the development of the antagonists. In this study, we employed a novel strategy for the development of receptor antagonists based on the design and synthesis of analog mixtures and the subsequent isolation and characterization of receptor anragonists from these mixtures. Using this strategy, a series of NPY analog mixtures was designed and synthesized. Screening of these mixtures using an NYP antagonist assay identified the receptor antagonists containing from 4 to 10 amino acids. The receptor antagonists inhibited the release of intracellular calcium elicited by NPY or PYY in human erythroleukemia (HEL) cells. On the other hand, to develop receptor antagonists of pancreastatin (PST), we needed a simple bioassay method for screening of receptor antagonists to PST.We therefore first examined the effects of PST on the increase in[Ca2+]i induced by several insulin secretagogues by using the dissociated rat pancreatic B-cells. We found that PST (1-100nM) dose-dependently inhibited the glucose-induced rise in[Ca2+]i insingle pancreatic islet cells. This observation allows us to develop an assay method for screening of the PST antagonists and to synthesize a series of PST analogs possibly used as receptor antagonists to PST.This study demonstrates that the analog mixture screening strategy significantly reduces the time and resources previously required for the development of receptor antagonists or agonists, and promises to enhance our ability to design new pharmacological agents for therapeutic uses.