Neuropeptide W-23 (human)

Deorphanised G-protein-coupled receptors represent new and expanding targets for drug development. Neuropeptide B (NPB) and W (NPW) have recently been identified as the cognate endogenous ligands for the orphan receptor GPR7, now designated as NPBW(1). NPB and NPW also bound to a second related orphan receptor, GPR8, now designated as NPBW(2) that is present in humans but not rats or mice. In humans, high levels of NPW mRNA have been visualised in the substantia nigra, whereas moderate expression levels have been detected in the amygdala and hippocampus. In peripheral tissues, expression of NPW mRNA has been confirmed in the progenital system, comprising the kidney, testis, uterus, ovary and placenta, and also in stomach homogenates. Immunocytochemical, molecular biological and autoradiography techniques have revealed a discrete CNS distribution for NPBW(1) in human, mouse and rat. Highest expression of NPBW(1) mRNA and protein was identified in the amygdala and hypothalamic nuclei known to regulate feeding behaviour. [(125)I]-NPW bound with a single high affinity to rat amygdala, K(D)=0.44 nM and 150 fmol mg(-1) protein. Physiological studies demonstrate that intracerebroventricular infusion of NPBW(1) ligands modulates feeding behaviour, regulates the release of corticosterone, prolactin and growth hormone while also manipulating pain pathway. Mouse knockout models of the gene encoding either NPB or NPBW(1) have a gender-specific phenotype, with moderate obesity evident in males but not females. Further investigation is required to elucidate the precise physiological role of NPB and NPW as neurotransmitters.

The structurally related orphan G-protein-coupled receptors GPR7 and GPR8 are expressed in the central nervous system, and their ligands have not been identified. Here, we report the identification of the endogenous ligand for both of these receptors. We purified the peptide ligand from porcine hypothalamus using stable Chinese hamster ovary cell lines expressing human GPR8 and cloned the cDNA encoding its precursor protein. The cDNA encodes two forms of the peptide ligand with lengths of 23 and 30 amino acid residues as mature peptides. We designated the two ligands neuropeptide W-23 (NPW23) and neuropeptide W-30 (NPW30). The amino acid sequence of NPW23 is completely identical to that of the N-terminal 23 residues of NPW30. Synthetic NPW23 and NPW30 activated and bound to both GPR7 and GPR8 at similar effective doses. Intracerebroventricular administration of NPW23 in rats increased food intake and stimulated prolactin release. These findings indicate that neuropeptide W is the endogenous ligand for both GPR7 and GPR8 and acts as a mediator of the central control of feeding and the neuroendocrine system.

Objective:Neuropeptide W (NPW), an endogenous ligand for the G protein-coupled receptor 7 (GPR7), was first found to make important roles in central nerve system. In periphery, NPW was also present and regulated intracellular calcium homeostasis by L-type calcium channels. This study was designed to discover the effects of NPW-GPR7 on the function of CaV1.2 calcium channels in the vascular smooth muscle cells (VSMCs) and vasotone of arterial vessels.Methods:By whole-cell patch clamp, we studied the effects of NPW-23, the active form of NPW, on the CaV1.2 channels in the heterologously transfected human embryonic kidney 293 cells and VSMCs isolated from rat. Living system was used to explore the physiological function of NPW-23 in arterial myogenic tone. To investigate the pathological relevance, NPW mRNA level of mesenteric arteries was measured in the hypertensive and normotensive rats.Results:NPW's receptor GPR7 was coexpressed with CaV1.2 channels in arterial smooth muscle. NPW-23 increased the ICa,L in transfected human embryonic kidney 293 cells and VSMCs via GPR7, which could be abrogated by phospholipase C (PLC)/protein kinase C (PKC) inhibitors, not protein kinase A or protein kinase G inhibitor. After NPW-23 application, the expression of pan phospho-PKC was increased; moreover, intracellular diacylglycerol level, the second messenger catalyzed by PLC, was increased 1.5-2-fold. Application with NPW-23 increased pressure-induced vasotone of the rat mesenteric arteries. Importantly, the expression of NPW was decreased in the hypertensive rats.Conclusion:NPW-23 regulates ICa,L via GPR7, which is mediated by PLC/PKC signaling, and such a mechanism plays a role in modulating vascular myogenic tone, which may involve in the development of vascular hypertension.