title: Phoenixin: A candidate pruritogen in the mouse.
abstract: Phoenixin (PNX) is a 14-amino acid amidated peptide (PNX-14) or an N-terminal extended 20-residue amidated peptide (PNX-20) recently identified in neural and non-neural tissue. Mass spectrometry analysis identified a major peak corresponding to PNX-14, with negligible PNX-20, in mouse spinal cord extracts. Using a previously characterized antiserum that recognized both PNX-14 and PNX-20, PNX-immunoreactivity (irPNX) was detected in a population of dorsal root ganglion (DRG) cells and in cell processes densely distributed to the superficial layers of the dorsal horn; irPNX cell processes were also detected in the skin. The retrograde tracer, Fluorogold, injected subcutaneously (s.c.) to the back of the cervical and thoracic spinal cord of mice, labeled a population of DRG, some of which were also irPNX. PNX-14 (2, 4 and 8 mg/kg) injected s.c.to the nape of the neck provoked dose-dependent repetitive scratching bouts directed to the back of the neck with the hindpaws. The number of scratching bouts varied from 16 to 95 in 30 min, commencing within 5 min post-injection and lasted 10-15 min. Pretreatment of mice at -20 min with nalfurafine (20 μg/kg, s.c.), the kappa opioid receptor agonist, significantly reduced the number of bouts induced by PNX-14 (4 mg/kg) compared with that of saline-pretreated mice. Our results suggest that the peptide, PNX-14, serves as one of the endogenous signal molecules transducing itch sensation in the mouse.
authors.affiliation: Department of Pharmacology, Temple University School of Medicine, Philadelphia, PA 19140, USA; Center for Substance Abuse Research, Temple University School of Medicine, Philadelphia, PA 19140, USA.
authors.forename: A
authors.initials: A
authors.lastname: Cowan
authors.affiliation: Phoenix Pharmaceuticals Inc., Burlingame, CA 94010, USA.
authors.forename: R-M
authors.initials: RM
authors.lastname: Lyu
authors.affiliation: Graduate Institute of Acupuncture Science, China Medical University, Taichung, Taiwan.
authors.forename: Y-H
authors.initials: YH
authors.lastname: Chen
authors.affiliation: Department of Pharmacology, Temple University School of Medicine, Philadelphia, PA 19140, USA.
authors.forename: S L
authors.initials: SL
authors.lastname: Dun
authors.affiliation: Phoenix Pharmaceuticals Inc., Burlingame, CA 94010, USA.
authors.forename: J-K
authors.initials: JK
authors.lastname: Chang
authors.affiliation: Department of Pharmacology, Temple University School of Medicine, Philadelphia, PA 19140, USA. Electronic address: ndun@temple.edu.
authors.forename: N J
authors.initials: NJ
authors.lastname: Dun
mesh_terms: D000818:Animals; D008297:Male; D051379:Mice; D000596:Amino Acids / Q000737:chemistry; D001522:Behavior, Animal / Q000187:drug effects; D066193:Cervical Cord / Q000378:metabolism; D005727:Ganglia, Spinal / Q000378:metabolism; D009333:Neck / Q000294:innervation; D010455:Peptides / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology / Q000502:physiology; D011537:Pruritus / Q000139:chemically induced; D012867:Skin / Q000378:metabolism; D013116:Spinal Cord / Q000378:metabolism; D008565:Membrane Proteins; D024101:Mitochondrial Proteins
chemical_list: D000596:Amino Acids; D010455:Peptides; C000731770:Smim20 protein, mouse; D008565:Membrane Proteins; D024101:Mitochondrial Proteins
keywords: dorsal root ganglion; itch; kappa opioid receptor; nalfurafine; primary afferent neuron; pruritogen