Effect of gastric bypass and gastric banding on proneurotensin levels in morbidly obese patients.
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.
Christ-Crain
Mirjam
M
Department of Endocrinology, Charterhouse Square, St. Bartholomews Hospital, London EC1M 6BQ, United Kingdom. christmj@bluewin.ch
Stoeckli
Rolf
R
Ernst
Andrea
A
Morgenthaler
Nils G
NG
Bilz
Stefan
S
Korbonits
Márta
M
Struck
Joachim
J
Bergmann
Andreas
A
Müller
Beat
B
Keller
Ulrich
U
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
D054439:Ghrelin; D020738:Leptin; D036361:Peptide Hormones; D011498:Protein Precursors; C411471:proneurotensin; D009496:Neurotensin