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Effect of Gastric Bypass and Gastric Banding on Proneurotensin Levels in Morbidly Obese Patients

Division of Endocrinology, Diabetes, and Clinical Nutrition (M.C.-C., R.S., S.B., B.M.,U.K.), University Hospital, CH-4031 Basel, Switzerland; SphingoTec GmbH (A.E.), D-16556 Borgsdorf, Germany; Research Department (N.G.M., J.S., A.B.), B.R.A.H.M.S. AG, D-16761 Hennigsdorf/Berlin, Germany; and Department of Endocrinology (M.C.-C., M.K.), St. Bartholomews Hospital, London EC1M 6BQ, United Kingdom

Address all correspondence and requests for reprints to: Mirjam Christ-Crain, M.D., Department of Endocrinology, Charterhouse Square, St. Bartholomews Hospital, London EC1M 6BQ, United Kingdom. E-mail: christmj{at}bluewin.ch.

Context: 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.

Design and Setting: This was a prospective observational study in a university hospital.

Participants and Main Outcome Measures: 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.

Conclusion: 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.

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				J. Drewe, S. Mihailovic, M. D'Amato, and C. Beglinger Regulation of Fat-Stimulated Neurotensin Secretion in Healthy Subjects J. Clin. Endocrinol. Metab., May 1, 2008; 93(5): 1964 - 1970. [Abstract] [Full Text] [PDF]