title: Role of nociceptin/orphanin FQ receptors in the decrease of mucosal mast cells caused by acute stress in the rat colon.
abstract: OBJECTIVE
  Mucosal mast cells (MMC) are mediators of the stress responses in the gastrointestinal tract. We examined the effect of acute cold-restraint stress and of the neuropeptide nociceptin/orphanin FQ (N/OFQ), implicated in the modulation of stress responses, on MMC density in the rat colon.
  
  
  METHODS
  Stress was induced by restraining the animals into individual cages at 3°C for 3h. N/OFQ and the selective N/OFQ peptide (NOP) receptor antagonist, UFP-101, were infused subcutaneously via Alzet osmotic minipumps. Segments of the distal colon were collected. MMCs were identified immunohistochemically with a monoclonal antibody to rat mast cell protease (RMCP) II and with a rabbit polyclonal antibody to CD117/c-kit receptor.
  
  
  RESULTS
  Acute stress caused a decrease in the density of MMCs in the rat colonic mucosa. Short-term peripheral infusion of N/OFQ (0.1 to 10 μg/kg/h for 4h) caused a dose-related reduction of MMC density. Peak reduction occurred after the 4-h infusion of N/OFQ, 1 μg/kg/h. Reduction was maintained after the 52-h infusion period and declined following 7 and 14 days of infusion. The infusion of N/OFQ (1μg/kg/h for 4h) in rats exposed to acute stress caused a decrease in MMC density comparable to that obtained with the single treatments. UFP-101, at the doses of 1 and 10 μg/kg/h, which itself had no significant effect on MMC density, when concurrently infused in stress-exposed rats, abolished the stress-induced decrease of MMC density.
  
  
  CONCLUSIONS
  Present results indicate that the peripheral N/OFQ-NOP system is involved in stress-induced reduction of MMC density.
authors.affiliation: Department of Human Anatomy, Pharmacology and Forensic Medicine, University of Parma, Parma, Italy.
authors.forename: Daniela
authors.initials: D
authors.lastname: Grandi
authors.forename: Maurizio
authors.initials: M
authors.lastname: Massi
authors.forename: Remo
authors.initials: R
authors.lastname: Guerrini
authors.forename: Girolamo
authors.initials: G
authors.lastname: Caló
authors.forename: Giuseppina
authors.initials: G
authors.lastname: Morini
mesh_terms: D000818:Animals; D003106:Colon / Q000378:metabolism; D004195:Disease Models, Animal; D004305:Dose-Response Relationship, Drug; D007413:Intestinal Mucosa / Q000378:metabolism*; D008297:Male; D008407:Mast Cells / Q000378:metabolism*; D018847:Opioid Peptides / Q000008:administration & dosage / Q000494:pharmacology*; D011817:Rabbits; D051381:Rats; D017208:Rats, Wistar; D011957:Receptors, Opioid / Q000378:metabolism*; D013315:Stress, Psychological / Q000503:physiopathology*; D013997:Time Factors; D000094942:Nociceptin Receptor; D000097629:Nociceptin
chemical_list: D018847:Opioid Peptides; D011957:Receptors, Opioid; D000094942:Nociceptin Receptor; D000097629:Nociceptin; C479838:(Nphe(1),Arg(14),Lys(15))N-OFQ NH(2)