title: Effect of gastric bypass and gastric banding on proneurotensin levels in morbidly obese patients.
abstract: BACKGROUND
  Neurotensin is produced mainly in the N cells of the ileum and has a role in appetite regulation; levels are decreased in obese subjects and increase after bariatric surgery. Mature neurotensin is very unstable, with a short half-life.
  
  
  OBJECTIVE
  The objective of this study was to compare baseline and postoperative levels of the more stable neurotensin precursor, proneurotensin/neuromedin (pro-NT/NMN), in patients after gastric banding, gastric bypass, and nonoperated controls, respectively, during long-term follow-up.
  
  
  METHODS
  This was a prospective observational study in a university hospital.
  
  
  METHODS
  Overnight fasting plasma pro-NT/NMN concentrations were measured with a new sandwich immunoassay in morbidly obese subjects at baseline and 6, 12, and 24 months after gastric banding (n = 8), Roux-en-Y gastric bypass (n = 5), and in nonoperated controls (n = 7).
  
  
  RESULTS
  After gastric bypass and banding, body weight decreased by (mean +/- sd) 29.5 +/- 5.5 and 22.8 +/- 5.9 kg, respectively. The decrease after 3 and 6 months was more pronounced after gastric bypass compared with gastric banding (P < 0.05). Plasma pro-NT/NMN levels in patients after gastric bypass increased from 246.3 +/- 174.3 pmol/liter on admission to 748.3 +/- 429.6 pmol/liter after 24 months (P < 0.01). In contrast, in patients with gastric banding, pro-NT/NMN concentrations remained stable (207.3 +/- 60.5 pmol/liter at admission, 226.6 +/- 116.8 pmol/liter after 24 months). Neither body weight nor plasma pro-NT/NMN levels changed in nonoperated controls.
  
  
  CONCLUSIONS
  Plasma pro-NT/NMN levels show a more pronounced increase after gastric bypass compared with gastric banding, suggesting that specific bariatric surgical procedures result in distinct alterations of gastrointestinal hormone metabolism. The more stable precursor pro-NT/NMN provides a new tool to quantify neurotensin levels in clinical practice.
authors.affiliation: Department of Endocrinology, Charterhouse Square, St. Bartholomews Hospital, London EC1M 6BQ, United Kingdom. christmj@bluewin.ch
authors.forename: Mirjam
authors.initials: M
authors.lastname: Christ-Crain
authors.forename: Rolf
authors.initials: R
authors.lastname: Stoeckli
authors.forename: Andrea
authors.initials: A
authors.lastname: Ernst
authors.forename: Nils G
authors.initials: NG
authors.lastname: Morgenthaler
authors.forename: Stefan
authors.initials: S
authors.lastname: Bilz
authors.forename: Márta
authors.initials: M
authors.lastname: Korbonits
authors.forename: Joachim
authors.initials: J
authors.lastname: Struck
authors.forename: Andreas
authors.initials: A
authors.lastname: Bergmann
authors.forename: Beat
authors.initials: B
authors.lastname: Müller
authors.forename: Ulrich
authors.initials: U
authors.lastname: Keller
mesh_terms: D000328:Adult; D005260:Female; D005500:Follow-Up Studies; D015390:Gastric Bypass; D054439:Ghrelin; D006801:Humans; D020738:Leptin / Q000097:blood; D008297:Male; D008875:Middle Aged; D009496:Neurotensin / Q000097:blood*; D009767:Obesity, Morbid / Q000097:blood* / Q000601:surgery*; D036361:Peptide Hormones / Q000097:blood; D011446:Prospective Studies; D011498:Protein Precursors / Q000097:blood*; D015431:Weight Loss
chemical_list: D054439:Ghrelin; D020738:Leptin; D036361:Peptide Hormones; D011498:Protein Precursors; C411471:proneurotensin; D009496:Neurotensin