title: Distribution of muscarinic acetylcholine receptor subtypes in the murine small intestine.
abstract: OBJECTIVE
  Serotonin stimulates enterocyte turnover in the small intestine and studies suggest this is mediated by neuronal signaling via a cholinergic pathway. Distribution of the five known muscarinic receptor subtypes (mAChRs) in the small intestine has not been fully studied, and their role in intestinal growth is unknown. We hypothesized that mAChRs have distinct anatomic distributions within the bowel, and that mAChRs present within intestinal crypts mediate the effects of acetylcholine on the small intestinal mucosa.
  
  
  METHODS
  Small intestine from male C57BL/6 mice ages 2, 4, 6, and 8weeks were harvested. RNA was isolated and cDNA synthesized for PCR-amplification of subtype specific mAChRs. Ileum was fixed with Nakane, embedded in epon, and immunofluorescence microscopy performed using polyclonal antibodies specific to each mAChR1-5.
  
  
  RESULTS
  All five mAChR subtypes were present in the mouse duodenum, jejunum, and ileum at all ages by RT-PCR. Immunofluorescence microscopy suggested the presence of mAChR1-5 in association with mature enterocytes along the villus and within the myenteric plexus. Only mAChR2 clearly localized to the crypt stem cell compartment, specifically co-localizing with Paneth cells at crypt bases.
  
  
  CONCLUSIONS
  Muscarinic receptors are widely distributed along the entire alimentary tract. mAChR2 appears to localize to the crypt stem cell compartment, suggesting it is a plausible regulator of stem cell activity. The location of mAChR2 to the crypt makes it a potential therapeutic target for treatment of intestinal disease such as short bowel syndrome. The exact cellular location and action of each mAChR requires further study.
authors.affiliation: Section of Pediatric Surgery, Yale School of Medicine, 333 Cedar Street, FMB 131, PO Box 20862, New Haven, CT 06520, United States.
authors.forename: Eleanor D
authors.initials: ED
authors.lastname: Muise
authors.affiliation: Section of Pediatric Surgery, Yale School of Medicine, 333 Cedar Street, FMB 131, PO Box 20862, New Haven, CT 06520, United States.
authors.forename: Neeru
authors.initials: N
authors.lastname: Gandotra
authors.affiliation: Section of Pediatric Surgery, Yale School of Medicine, 333 Cedar Street, FMB 131, PO Box 20862, New Haven, CT 06520, United States.
authors.forename: John J
authors.initials: JJ
authors.lastname: Tackett
authors.affiliation: Section of Pediatric Surgery, Yale School of Medicine, 333 Cedar Street, FMB 131, PO Box 20862, New Haven, CT 06520, United States.
authors.forename: Michaela C
authors.initials: MC
authors.lastname: Bamdad
authors.affiliation: Section of Pediatric Surgery, Yale School of Medicine, 333 Cedar Street, FMB 131, PO Box 20862, New Haven, CT 06520, United States. Electronic address: robert.cowles@yale.edu.
authors.forename: Robert A
authors.initials: RA
authors.lastname: Cowles
mesh_terms: D000818:Animals; D005455:Fluorescent Antibody Technique; D007413:Intestinal Mucosa / Q000737:chemistry* / Q000166:cytology / Q000254:growth & development / Q000648:ultrastructure*; D007421:Intestine, Small / Q000737:chemistry* / Q000166:cytology / Q000254:growth & development / Q000648:ultrastructure*; D008297:Male; D008810:Mice, Inbred C57BL; D008856:Microscopy, Fluorescence; D011976:Receptors, Muscarinic / Q000032:analysis*; D013234:Stem Cells / Q000737:chemistry / Q000166:cytology
chemical_list: D011976:Receptors, Muscarinic
keywords: Enteric nervous system; Intestinal crypt; Muscarinic acetylcholine receptor; Paneth cell; Stem cell compartment