Sialorphin, a natural inhibitor of rat membrane-bound neutral endopeptidase that displays analgesic activity.
Sialorphin is an exocrine and endocrine signaling mediator, which has been identified by a genomic approach. It is synthesized predominantly in the submandibular gland and prostate of adult rats in response to androgen steroids and is released locally and systemically in response to stress. We now demonstrate that the cell surface molecule to which sialorphin binds in vivo in the rat kidney is the membrane-anchored neutral endopeptidase (neprilysin; NEP, EC 3.4.24.11). NEP plays an important role in nervous and peripheral tissues, as it turns off several peptide-signaling events at the cell surface. We show that sialorphin prevents spinal and renal NEP from breaking down its two physiologically relevant substrates, substance P and Met-enkephalin in vitro. Sialorphin inhibited the breakdown of substance P with an IC50 of 0.4-1 microM and behaved as a competitive inhibitor. In vivo, i.v. sialorphin elicited potent antinociceptive responses in two behavioral rat models of injury-induced acute and tonic pain, the pin-pain test and formalin test. The analgesia induced by 100-200 mcicrog/kg doses of sialorphin required the activation of mu- and delta-opioid receptors, consistent with the involvement of endogenous opioid receptors in enkephalinergic transmission. We conclude that sialorphin protects endogenous enkephalins released after nociceptive stimuli by inhibiting NEP in vivo. Sialorphin is a natural systemically active regulator of NEP activity. Furthermore, our study provides evidence that it is a physiological modulator of pain perception after injury and might be the progenitor of a new class of therapeutic molecules.
Rougeot
Catherine
C
Unité de Génétique et Biochimie du Développement, Centre National de la Recherche Scientifique, Unité de Recherche Associée 1960, Institut Pasteur, 25 Rue du Docteur Roux 75724, Paris Cedex 15, France. crougeot@pasteur.fr
Messaoudi
Michaël
M
Hermitte
Véronique
V
Rigault
Anne Gaëlle
AG
Blisnick
Thierry
T
Dugave
Christophe
C
Desor
Didier
D
Rougeon
François
F
D000595:Amino Acid Sequence; D000700:Analgesics / Q000494:pharmacology* / Q000627:therapeutic use; D000818:Animals; D004744:Enkephalin, Methionine / Q000378:metabolism; D005557:Formaldehyde / Q000633:toxicity; D006020:Glycopeptides / Q000494:pharmacology; D007668:Kidney / Q000187:drug effects / Q000201:enzymology; D007930:Leucine / Q000031:analogs & derivatives* / Q000494:pharmacology; D008297:Male; D008565:Membrane Proteins / Q000037:antagonists & inhibitors / Q000502:physiology*; D008969:Molecular Sequence Data; D009271:Naltrexone / Q000031:analogs & derivatives* / Q000494:pharmacology; D015260:Neprilysin / Q000037:antagonists & inhibitors*; D010146:Pain / Q000139:chemically induced / Q000188:drug therapy*; D010147:Pain Measurement; D011467:Prostate / Q000378:metabolism; D011480:Protease Inhibitors / Q000494:pharmacology* / Q000627:therapeutic use; D011498:Protein Precursors / Q000737:chemistry / Q000494:pharmacology / Q000502:physiology* / Q000627:therapeutic use; D051381:Rats; D017208:Rats, Wistar; D017465:Receptors, Opioid, delta / Q000187:drug effects / Q000502:physiology; D017450:Receptors, Opioid, mu / Q000187:drug effects / Q000502:physiology; D012471:Salivary Proteins and Peptides / Q000737:chemistry / Q000494:pharmacology / Q000502:physiology* / Q000627:therapeutic use; D013116:Spinal Cord / Q000187:drug effects / Q000201:enzymology; D013363:Submandibular Gland / Q000378:metabolism; D013373:Substance P / Q000378:metabolism; D015244:Thiorphan / Q000494:pharmacology; D014947:Wounds and Injuries / Q000503:physiopathology
D000700:Analgesics; D006020:Glycopeptides; D008565:Membrane Proteins; D011480:Protease Inhibitors; D011498:Protein Precursors; D017465:Receptors, Opioid, delta; D017450:Receptors, Opioid, mu; D012471:Salivary Proteins and Peptides; C066861:Smr3b protein, rat; D005557:Formaldehyde; D013373:Substance P; C051844:norbinaltorphimine; D004744:Enkephalin, Methionine; D009271:Naltrexone; D015244:Thiorphan; D015260:Neprilysin; D007930:Leucine; C012211:ubenimex; C008890:phosphoramidon