title: Linaclotide inhibits colonic nociceptors and relieves abdominal pain via guanylate cyclase-C and extracellular cyclic guanosine 3',5'-monophosphate.
abstract: OBJECTIVE
  Linaclotide is a minimally absorbed agonist of guanylate cyclase-C (GUCY2C or GC-C) that reduces symptoms associated with irritable bowel syndrome with constipation (IBS-C). Little is known about the mechanism by which linaclotide reduces abdominal pain in patients with IBS-C.
  
  
  METHODS
  We determined the effects of linaclotide on colonic sensory afferents in healthy mice and those with chronic visceral hypersensitivity. We assessed pain transmission by measuring activation of dorsal horn neurons in the spinal cord in response to noxious colorectal distention. Levels of Gucy2c messenger RNA were measured in tissues from mice using quantitative reverse transcription polymerase chain reaction and in situ hybridization. We used human intestinal cell lines to measure release of cyclic guanosine-3',5'-monophosphate (cGMP) by linaclotide. We performed a post-hoc analysis of data from a phase III, double-blind, parallel-group study in which 805 patients with IBS-C were randomly assigned to groups given an oral placebo or 290 μg linaclotide once daily for 26 weeks. We quantified changes in IBS-C symptoms, including abdominal pain.
  
  
  RESULTS
  In mice, linaclotide inhibited colonic nociceptors with greater efficacy during chronic visceral hypersensitivity. Intra-colonic administration of linaclotide reduced signaling of noxious colorectal distention to the spinal cord. The colonic mucosa, but not neurons, was found to express linaclotide's target, GC-C. The downstream effector of GC-C, cGMP, was released after administration of linaclotide and also inhibited nociceptors. The effects of linaclotide were lost in Gucy2c(-/-) mice and prevented by inhibiting cGMP transporters or removing the mucosa. During 26 weeks of linaclotide administration, a significantly greater percentage of patients (70%) had at least a 30% reduction in abdominal pain compared with patients given placebo (50%).
  
  
  CONCLUSIONS
  We have identified an analgesic mechanism of linaclotide: it activates GC-C expressed on mucosal epithelial cells, resulting in the production and release of cGMP. This extracellular cGMP acts on and inhibits nociceptors, thereby reducing nociception. We also found that linaclotide reduces chronic abdominal pain in patients with IBS-C.
authors: Nerve-Gut Research Laboratory, Discipline of Medicine, Faculty of Health Sciences, The University of Adelaide, Adelaide, South Australia, Australia; Department of Gastroenterology and Hepatology, Hanson Institute, Royal Adelaide Hospital, Adelaide, South Australia, Australia.
authors: Joel
authors: J
authors: Castro
authors: Andrea M
authors: AM
authors: Harrington
authors: Patrick A
authors: PA
authors: Hughes
authors: Christopher M
authors: CM
authors: Martin
authors: Pei
authors: P
authors: Ge
authors: Courtney M
authors: CM
authors: Shea
authors: Hong
authors: H
authors: Jin
authors: Sarah
authors: S
authors: Jacobson
authors: Gerhard
authors: G
authors: Hannig
authors: Elizabeth
authors: E
authors: Mann
authors: Mitchell B
authors: MB
authors: Cohen
authors: James E
authors: JE
authors: MacDougall
authors: Bernard J
authors: BJ
authors: Lavins
authors: Caroline B
authors: CB
authors: Kurtz
authors: Inmaculada
authors: I
authors: Silos-Santiago
authors: Jeffrey M
authors: JM
authors: Johnston
authors: Mark G
authors: MG
authors: Currie
authors: L Ashley
authors: LA
authors: Blackshaw
authors: Stuart M
authors: SM
authors: Brierley
mesh_terms: D015746:Abdominal Pain / Q000139:chemically induced / Q000517:prevention & control*; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000818:Animals; D018938:Caco-2 Cells; D002460:Cell Line; D003106:Colon / Q000187:drug effects / Q000294:innervation* / Q000473:pathology; D006152:Cyclic GMP / Q000502:physiology*; D004195:Disease Models, Animal; D004311:Double-Blind Method; D005260:Female; D006162:Guanylate Cyclase / Q000502:physiology*; D006801:Humans; D043183:Irritable Bowel Syndrome / Q000139:chemically induced / Q000517:prevention & control; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008875:Middle Aged; D045265:Natriuretic Peptides / Q000494:pharmacology; D009619:Nociceptors / Q000187:drug effects* / Q000502:physiology; D010455:Peptides / Q000494:pharmacology* / Q000627:therapeutic use*; D017461:Receptors, Atrial Natriuretic Factor / Q000502:physiology; D000074261:Receptors, Enterotoxin; D050705:Receptors, Guanylate Cyclase-Coupled / Q000502:physiology; D018000:Receptors, Peptide / Q000502:physiology; D016896:Treatment Outcome; D014302:Trinitrobenzenesulfonic Acid / Q000009:adverse effects
chemical_list: D045265:Natriuretic Peptides; D010455:Peptides; D018000:Receptors, Peptide; C084362:uroguanylin; D014302:Trinitrobenzenesulfonic Acid; C000613654:GUCY2C protein, human; D006162:Guanylate Cyclase; C000613655:Gucy2c protein, mouse; D017461:Receptors, Atrial Natriuretic Factor; D000074261:Receptors, Enterotoxin; D050705:Receptors, Guanylate Cyclase-Coupled; C073616:atrial natriuretic factor receptor C; D006152:Cyclic GMP; C523483:linaclotide
keywords: Analgesia; CRD; CVH; DH; GC-C; IBS; IBS-C; IR; Signaling Transduction; TNBS; cGMP; chronic visceral hypersensitivity; colorectal distention; cyclic guanosine-3′,5′-monophosphate; dorsal horn; guanylate cyclase-C; immunoreactivity; irritable bowel syndrome; irritable bowel syndrome with constipation; pERK; phosphorylated MAP kinase ERK 1/2; trinitrobenzene sulfonic acid