Roux-en-Y Gastric Bypass Operation in Rats

Abstract

Currently, the most effective therapy for the treatment of morbid obesity to induce significant and maintained body weight loss with a proven mortality benefit is bariatric surgery. Consequently, there has been a steady rise in the number of bariatric operations done worldwide in recent years with the Roux-en-Y gastric bypass (gastric bypass) being the most commonly performed operation. Against this background, it is important to understand the physiological mechanisms by which gastric bypass induces and maintains body weight loss. These mechanisms are yet not fully understood, but may include reduced hunger and increased satiation, increased energy expenditure, altered preference for food high in fat and sugar, altered salt and water handling of the kidney as well as alterations in gut microbiota. Such changes seen after gastric bypass may at least partly stem from how the surgery alters the hormonal milieu because gastric bypass increases the postprandial release of peptide-YY (PYY) and glucagon-like-peptide-1 (GLP-1), hormones that are released by the gut in the presence of nutrients and that reduce eating. During the last two decades numerous studies using rats have been carried out to further investigate physiological changes after gastric bypass. The gastric bypass rat model has proven to be a valuable experimental tool not least as it closely mimics the time profile and magnitude of human weight loss, but also allows researchers to control and manipulate critical anatomic and physiologic factors including the use of appropriate controls. Consequently, there is a wide array of rat gastric bypass models available in the literature reviewed elsewhere in more detail. The description of the exact surgical technique of these models varies widely and differs e.g. in terms of pouch size, limb lengths, and the preservation of the vagal nerve. If reported, mortality rates seem to range from 0 to 35%. Furthermore, surgery has been carried out almost exclusively in male rats of different strains and ages. Pre- and postoperative diets also varied significantly. Technical and experimental variations in published gastric bypass rat models complicate the comparison and identification of potential physiological mechanisms involved in gastric bypass. There is no clear evidence that any of these models is superior, but there is an emerging need for standardization of the procedure to achieve consistent and comparable data. This article therefore aims to summarize and discuss technical and experimental details of our previously validated and published gastric bypass rat model.

Gastric Bypass Improves β-Cell Function and Increases β-Cell Mass in a Porcine Model

“…Since pancreatic anatomy in pigs resembles the human more than the rodent (18), a porcine RYGB model was developed. A potential limitation of the study was that although RYGB provokes massive weight loss in morbidly obese humans (1) and in obese rodent models (17), RYGB pigs displayed similar body weight development as the sham pigs. Whether this is related to the use of nonobese, nondiabetic pigs or if it is due to species differences remains to be elucidated, but weight loss has been reported to be a function of preoperative excess weight in humans (19).…”

“…Studies aiming to uncover the mechanism have been performed in rodents (17). However, due to the pronounced differences in food composition, gastrointestinal tract, and pancreas physiology, these results may not be easily translated into the human.…”

Effect of bariatric surgery combined with medical therapy versus intensive medical therapy or calorie restriction and weight loss on glycemic control in Zucker diabetic fatty rats

“…After exposure and careful mobilization of the gastro-esophageal junction, the stomach was transected just below the gastro-esophageal junction to create a small gastric pouch about 2% of the original stomach size. The stomach remnant was subsequently closed, and the small gastric pouch was anastomosed end-to-side to the alimentary limb, which was ϳ500 mm in length (4).…”

Roux-en-Y gastric bypass surgery in rats alters gut microbiota profile along the intestine

“…Rats were then placed in a supine position on a heating pad and positioned in a nose cone to maintain anesthesia (2%-4% isoflurane in oxygen, 0.5 L/min) for the duration of the surgery. All surgeries were conducted as previously described [11][12][13] …”