Neuropeptide Y: The story, the players, the outcomes

Abstract

Neuropeptide Y (NPY) is a peptide consisted of 36 amino acids. It is designated by a capital letter Y due to the presence of many tyrosine residues which are abbreviated by the letter Y in the single letter amino acid code. NPY is one of the most evolutionary conserved peptides, originally isolated from pig brain (Tatemoto et al. 1982; Larhammar 1996). Due to a very wide tissue distribution of NPY and its significance for the human and animal physiology, peptides with high structural homology to NPY, e.g., peptide YY (PYY), pancreatic polypeptide (PP) and their truncated forms NPY2-36, NPY3-36 and PYY3-36, sharing amino acid backbone that forms a hair-pin turn called the PP-fold (Fuhlendorff et al. 1990), are now specified as members of NPY family. NPY was previously considered a companion and amplifier of norepinephrine activity. It is now known that NPY could be stored alone in small vesicles of sympathetic nerves, and in combination with catecholamines in large vesicles (Fried et al. 1985). Although NPY is preferentially released under conditions of high frequency nerve stimulation, the endogenous NPY modulates the effects of norepinephrine at both high and low levels of sympathetic nerve activity (Han et al. 1998).