title: Inhibiting endocannabinoid biosynthesis: a novel approach to the treatment of constipation.
abstract: OBJECTIVE
  Endocannabinoids are a family of lipid mediators involved in the regulation of gastrointestinal (GI) motility. The expression, localization and function of their biosynthetic enzymes in the GI tract are not well understood. Here, we examined the expression, localization and function of the enzyme diacylglycerol lipase-α (DAGLα), which is involved in biosynthesis of the endocannabinoid 2-arachidonoylglycerol (2-AG).
  
  
  METHODS
  Cannabinoid CB1 receptor-deficient, wild-type control and C3H/HeJ mice, a genetically constipated strain, were used. The distribution of DAGLα in the enteric nervous system was examined by immunohistochemistry. Effects of the DAGL inhibitors, orlistat and OMDM-188 on pharmacologically induced GI hypomotility were assessed by measuring intestinal contractility in vitro and whole gut transit or faecal output in vivo. Endocannabinoid levels were measured by mass spectrometry.
  
  
  RESULTS
  DAGLα was expressed throughout the GI tract. In the intestine, unlike DAGLβ, DAGLα immunoreactivity was prominently expressed in the enteric nervous system. In the myenteric plexus, it was colocalized with the vesicular acetylcholine transporter in cholinergic nerves. In normal mice, inhibiting DAGL reversed both pharmacologically reduced intestinal contractility and pharmacologically prolonged whole gut transit. Moreover, inhibiting DAGL normalized faecal output in constipated C3H/HeJ mice. In colons incubated with scopolamine, 2-AG was elevated while inhibiting DAGL normalized 2-AG levels.
  
  
  CONCLUSIONS
  DAGLα was expressed in the enteric nervous system of mice and its inhibition reversed slowed GI motility, intestinal contractility and constipation through 2-AG and CB1 receptor-mediated mechanisms. Our data suggest that DAGLα inhibitors may be promising candidates for the treatment of constipation.
authors: Hotchkiss Brain Institute and Snyder Institute for Chronic Diseases, Department of Physiology and Pharmacology, University of Calgary, Calgary, AB, Canada.
authors: M
authors: M
authors: Bashashati
authors: Division of Gastroenterology, Department of Medicine, University of Calgary, Calgary, AB, Canada.
authors: Y
authors: Y
authors: Nasser
authors: Hotchkiss Brain Institute and Snyder Institute for Chronic Diseases, Department of Physiology and Pharmacology, University of Calgary, Calgary, AB, Canada.
authors: C M
authors: CM
authors: Keenan
authors: Hotchkiss Brain Institute and Snyder Institute for Chronic Diseases, Department of Physiology and Pharmacology, University of Calgary, Calgary, AB, Canada.
authors: W
authors: W
authors: Ho
authors: Endocannabinoid Research Group, Istituto di Chimica Biomolecolare, Consiglio Nazionale delle Ricerche, Pozzuoli, Italy.
authors: F
authors: F
authors: Piscitelli
authors: Dipartimento di Chimica e Tecnologie del Farmaco, Sapienza Università di Roma, Rome, Italy.
authors: M
authors: M
authors: Nalli
authors: Department of Psychological and Brain Sciences, Gill Center for Biomolecular Science, Indiana University, Bloomington, IN, USA.
authors: K
authors: K
authors: Mackie
authors: Division of Gastroenterology, Department of Medicine, University of Calgary, Calgary, AB, Canada.|II Medical Department, Klinikum Groshadern, Ludwig Maximilians University of Munich, Munich, Germany.
authors: M A
authors: MA
authors: Storr
authors: Endocannabinoid Research Group, Istituto di Chimica Biomolecolare, Consiglio Nazionale delle Ricerche, Pozzuoli, Italy.
authors: V
authors: V
authors: Di Marzo
authors: Hotchkiss Brain Institute and Snyder Institute for Chronic Diseases, Department of Physiology and Pharmacology, University of Calgary, Calgary, AB, Canada.
authors: K A
authors: KA
authors: Sharkey
mesh_terms: D000818:Animals; D001095:Arachidonic Acids / Q000096:biosynthesis*; D003248:Constipation / Q000188:drug therapy* / Q000235:genetics / Q000503:physiopathology; D063388:Endocannabinoids / Q000096:biosynthesis*; D005769:Gastrointestinal Motility / Q000187:drug effects; D005989:Glycerides / Q000096:biosynthesis*; D007532:Isoleucine / Q000031:analogs & derivatives / Q000494:pharmacology; D007783:Lactones / Q000494:pharmacology; D008071:Lipoprotein Lipase / Q000037:antagonists & inhibitors* / Q000378:metabolism; D008297:Male; D013058:Mass Spectrometry; D051379:Mice; D008809:Mice, Inbred C3H; D008810:Mice, Inbred C57BL; D000077403:Orlistat; D043884:Receptor, Cannabinoid, CB1 / Q000378:metabolism*; D012601:Scopolamine / Q000494:pharmacology
chemical_list: D001095:Arachidonic Acids; D063388:Endocannabinoids; D005989:Glycerides; D007783:Lactones; C585831:N-formyl-isoleucine-1-((3-hexyl-4-oxo-2-oxetanyl)methyl)dodecyl ester; D043884:Receptor, Cannabinoid, CB1; D007532:Isoleucine; C094503:glyceryl 2-arachidonate; D000077403:Orlistat; D012601:Scopolamine; D008071:Lipoprotein Lipase