title: Endogenous peptide YY and neuropeptide Y inhibit colonic ion transport, contractility and transit differentially via Y₁ and Y₂ receptors.
abstract: OBJECTIVE
  Peptide YY (PYY) and neuropeptide Y (NPY) activate Y receptors, targets under consideration as treatments for diarrhoea and other intestinal disorders. We investigated the gastrointestinal consequences of selective PYY or NPY ablation on mucosal ion transport, smooth muscle activity and transit using wild-type, single and double peptide knockout mice, comparing mucosal responses with those from human colon.
  
  
  METHODS
  Mucosae were pretreated with a Y₁ (BIBO3304) or Y₂ (BIIE0246) receptor antagonist and changes in short-circuit current recorded. Colonic transit and colonic migrating motor complexes (CMMCs) were assessed in vitro and upper gastrointestinal and colonic transit measured in vivo.
  
  
  RESULTS
  Y receptor antagonists revealed tonic Y₁ and Y₂ receptor-mediated antisecretory effects in human and wild-type mouse colon mucosae. In both, Y₁ tone was epithelial while Y₂ tone was neuronal. Y₁ tone was reduced 90% in PYY⁻/⁻ mucosa but unchanged in NPY⁻/⁻ tissue. Y₂ tone was partially reduced in NPY⁻/⁻ or PYY⁻/⁻ mucosae and abolished in tetrodotoxin-pretreated PYY⁻/⁻ tissue. Y₁ and Y₂ tone were absent in NPYPYY⁻/⁻ tissue. Colonic transit was inhibited by Y₁ blockade and increased by Y₂ antagonism indicating tonic Y₁ excitation and Y₂ inhibition respectively. Upper GI transit was increased in PYY⁻/⁻ mice only. Y₂ blockade reduced CMMC frequency in isolated mouse colon.
  
  
  CONCLUSIONS
  Endogenous PYY and NPY induced significant mucosal antisecretory tone mediated by Y₁ and Y₂ receptors, via similar mechanisms in human and mouse colon mucosa. Both peptides contributed to tonic Y₂-receptor-mediated inhibition of colonic transit in vitro but only PYY attenuated upper GI transit.
authors: King's College London, Wolfson Centre for Age-Related Diseases, Guy's Campus, London, UK.
authors: I R
authors: IR
authors: Tough
authors: S
authors: S
authors: Forbes
authors: R
authors: R
authors: Tolhurst
authors: M
authors: M
authors: Ellis
authors: H
authors: H
authors: Herzog
authors: J C
authors: JC
authors: Bornstein
authors: H M
authors: HM
authors: Cox
mesh_terms: D000368:Aged; D000818:Animals; D003106:Colon / Q000378:metabolism / Q000502:physiology*; D005260:Female; D005772:Gastrointestinal Transit / Q000235:genetics / Q000502:physiology*; D006801:Humans; D007413:Intestinal Mucosa / Q000378:metabolism / Q000502:physiology; D017136:Ion Transport / Q000502:physiology; D008297:Male; D051379:Mice; D057507:Mice, 129 Strain; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009119:Muscle Contraction / Q000502:physiology; D009130:Muscle, Smooth / Q000378:metabolism / Q000502:physiology; D009478:Neuropeptide Y / Q000235:genetics / Q000378:metabolism*; D019894:Peptide YY / Q000235:genetics / Q000378:metabolism*; D017476:Receptors, Neuropeptide Y / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*
chemical_list: D009478:Neuropeptide Y; D017476:Receptors, Neuropeptide Y; C097212:neuropeptide Y-Y1 receptor; C095889:neuropeptide Y2 receptor; D019894:Peptide YY