Lessons Learned from Gastric Bypass Operations in Rats

Abstract

Numerous studies using gastric bypass rat models have been recently conducted to uncover underlying physiological mechanisms of Roux-en-Y gastric bypass. Reflecting on lessons learned from gastric bypass rat models may thus aid the development of gastric bypass models in mice and other species. This review aims to discuss technical and experimental details of published gastric bypass rat models to understand advantages and limitations of this experimental tool. The review is based on PubMed literature using the search terms ‘animal model’, ‘rodent model’, ‘bariatric surgery’, ‘gastric bypass’, and ‘Roux-en-Y gastric bypass’. All studies published up until February 2011 were included. 32 studies describing 15 different rat gastric bypass models were included. Description of surgical technique differs in terms of pouch size, limb lengths, preservation of the vagal nerve, and mortality rate. Surgery was carried out 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 comparison and identification of potential physiological mechanisms involved in gastric bypass. In summary, 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.

Gastric Bypass Increases Ethanol and Water Consumption in Diet-Induced Obese Rats

“…the rat stomach contains a thin walled rumen which cannot be surgically divided), the operation in rats is not as restrictive as in humans and the pouch-size greatly varies across laboratories (for a review, see [25]). Furthermore, RYGB procedures differ by surgeon, and in our study a 30 cm portion of the bilio-pancreatic limb was bypassed as opposed to 10–16 cm portion used in studies reporting less food intake [20–21, 25]. Greater limb bypass means less nutrient absorption, which may contribute to an increased drive for food intake due to the likely decrease in nutrient absorption.…”

Animal models for diabetes: Understanding the pathogenesis and finding new treatments

“…Models of bariatric surgery have been developed in both mice [183] and rats [184], as well as other larger animals such as pigs [185], and have been shown to have similarly beneficial effects on glucose homeostasis to those observed clinically. The use of these surgical animal models has established a link between bariatric surgery and improved islet structure and function [185], whilst studies in Lepr db/db mice have also provided evidence for circulating factors released from the gut that are able to influence insulin target tissues [186].…”

Roux-en-Y gastric bypass: effects on feeding behavior and underlying mechanisms

“…However, these animal studies should be interpreted with caution due to important differences in the rodent stomach and rodent feeding behavior (106,107), both of which could adversely affect interpretation of RYGBP-induced outcomes. Furthermore, changes in rodent feeding following bariatric surgery are often not prolonged (108); thus, delineation of the relevant biological processes is challenging.…”