A Rodent Model of Adjustable Gastric Band Surgery—Implications for the Understanding of Underlying Mechanisms
(Impact Factor: 3.75).
05/2009; 19(5):625-631. DOI: 10.1007/s11695-008-9751-0
Bariatric surgery is currently the only anti-obesity therapy that can deliver weight loss of up to 20–30% of body weight. Laparoscopic adjustable gastric banding (LAGB) and Roux-en-y gastric bypass are the most commonly performed of these surgeries. The mechanisms by which LAGB initiates an increase in satiety remain completely unknown. The aim of this study is to establish a rodent model of adjustable gastric banding (AGB) that will enable investigation of these mechanisms.
Sprague–Dawley rats were implanted with adjustable gastric bands immediately below the gastro-esophageal junction around the glandular stomach. This band, as in humans, can be inflated via an exteriorized port resulting in an incremental impact on the stomach.
Rats with an incremental inflation of the AGB showed a clear stepwise reduction in food intake and body weight. Normal food intake and body weight gain were restored with band deflation. Barium-assisted X-ray of the stomach showed the formation of a small gastric pouch proximal to the inflated band in a manner analogous to the human LAGB.
This is the first animal model of the AGB that allows incremental inflation for optimal tightening of the band in the conscious animal with corresponding effects on food intake and body weight. This model will allow measurement of acute and chronic neural and hormonal changes following activation of the band in the conscious animal and will provide the potential to inform and improve surgical approaches that are at the forefront of obesity treatments.
Available from: Kirk Habegger
- "AGB surgery was performed in anesthetized rats (isoflurane) as previously described by Kampe et al. (16) and depicted in Fig. 1. Briefly, rats received laparotomy followed by isolation of the stomach and removal of the forestomach (fundectomy) using an ETS-FLEX 35-mm staple gun (Ethicon Endo-Surgery, Somerville, NJ). "
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ABSTRACT: Bariatric procedures vary in efficacy, but overall are more effective than behavioral and pharmaceutical treatment. Roux-en-Y Gastric Bypass causes increased secretion of Glucagon-like peptide 1 (GLP-1), and reduces body weight more than adjustable gastric banding (AGB), which does not trigger increased GLP-1 secretion. Since GLP-1-based drugs consistently reduce body weight, we hypothesized that GLP-1 receptor (GLP-1R) agonists would augment the effects of AGB. Male Long Evans rats with diet-induced obesity received AGB implantation or sham surgery. GLP-1R agonism, cannabinoid receptor-1 (CB1-R) antagonism, or vehicle was combined with inflation to evaluate interaction between AGB and pharmacological treatments. GLP1-R agonism reduced BW in both sham and AGB rats (left un-inflated) compared to vehicle-treated animals. Subsequent band inflation was ineffective in vehicle-treated rats, but enhanced weight loss stimulated by GLP1-R agonism. In contrast, there were no additional BW loss when CB1-R antagonism was given with AGB. We found band inflation to trigger neural activation in areas of the nucleus of the solitary tract known to be targeted by GLP1-R agonism, offering potential mechanism for the interaction. These data show that GLP-1R agonism, but not CB1-R antagonism, improves weight loss achieved by AGB, and suggest an opportunity to optimize bariatric surgery with adjunctive pharmacotherapy.
Available from: Anna Korin
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ABSTRACT: Laparoscopic adjustable gastric bands (LAGB) are a safe and effective treatment for obesity. Conflicting data exist concerning their effect on the esophagus, gastroesophageal junction, and mechanism of action. These patients will increasingly require accurate assessment of their esophageal function.
Twenty LAGB patients underwent high-resolution video manometry with the LAGB empty, 20% under, 20% over, and at their optimal volume. Twenty obese controls were also studied. Effects on esophageal motility, the lower esophageal sphincter (LES), and the gastroesophageal junction were measured. Transit during liquid and semisolid swallows was assessed.
The intraluminal pressure at the level of LAGB was a mean of 26.9 (19.8) mm Hg. This pressure varied depending on the volume within the LAGB and was separate to and distal to the lower esophageal sphincter LES. The LES was attenuated compared to controls (10 vs 18 mm Hg; p < 0.01) although relaxed normally. Esophageal motility was well preserved at optimal volume compared to 20% overfilled, with 77% normal swallows vs 51%, p = 0.008. Repetitive esophageal contractions were observed in 40% of swallows at optimal volume compared to 16% in controls, p = 0.024. In comparison to controls, the transit of liquid, 21 vs 8 s (p < 0.001), and semisolids, 50 vs 16 s (p < 0.001), was delayed.
In LAGB patients, the LES is attenuated, although relaxes normally. Esophageal motility is preserved, although disrupted by overfilling the band. In the optimally adjusted LAGB, a delay in transit of liquids and semisolids through the esophagus and band is produced, along with an increase in repeated esophageal contractions.
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ABSTRACT: Bariatric surgery is considered the most effective current treatment for morbid obesity. Since the first publication of an article by Kremen, Linner, and Nelson, many experiments have been performed using animal models. The initial experiments used only malabsorptive procedures like intestinal bypass which have largely been abandoned now. These experimental models have been used to assess feasibility and safety as well as to refine techniques particular to each procedure. We will discuss the surgical techniques and the postsurgical physiology of the four major current bariatric procedures (namely, Roux-en-Y gastric bypass, gastric banding, sleeve gastrectomy, and biliopancreatic diversion). We have also reviewed the anatomy and physiology of animal models. We have reviewed the literature and presented it such that it would be a reference to an investigator interested in animal experiments in bariatric surgery. Experimental animal models are further divided into two categories: large mammals that include dogs, cats, rabbits, and pig and small mammals that include rats and mice.
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