The overall goal of these surgical interventions is to measure the metabolic effects of sleeve gastrectomy and Roux-en-Y bypass in a mouse model. This method can help answer key question in the obesity and metabolism fields about the pathway on molecular mechanism involved in the metabolic gains observed after bariatric surgery. The main advantage of these techniques is that they stimulate the clinical consequences of bariatric surgery, as observed in human patient in a mouse model.
For a sleeve gastrectomy, after confirming the appropriate level of anesthesia by toe pinch, apply ointment to the mouse's eyes, and use an electric razor to shave the abdomen from sternum to pelvis. Cover the abdomen in plastic wrap, and place the animal in the supine position on the heating pad. Cut a window in the plastic wrap, and disinfect the skin with povidone iodine solution.
Then place the animal under a binocular microscope, and use a scalpel to make a midline skin incision from the sternum to the middle of the abdomen. Next, protect the skin with a sterile compress soaked with 37 degrees Celsius saline solution, and use cotton swabs to gently mobilize the stomach, freeing the organ from the lateral close connective tissue attachments to allow its complete externalization. Place a hemostatic collagen compress behind the reflected organ.
Then use 8.0 non-absorbable sutures to ligate the pylorus and esophagus vessels along the stomach greater curvature, followed by a gastrotomy on the anatomical line between the pyloric and cardiac regions of stomach. Use two moistened cotton swabs to remove any residual food from each side of the stomach. Then use micro scissors to cut the stomach along the boundary between the fundus and the corpus, and close the stomach opening with 8.0 non-absorbable sutures from the gastro-esophageal junction to the end of the incision.
Complete the stomach resection along the greater curvature to remove approximately 80%of the stomach, applying a hemostatic collagen compress as appropriate. Close the opening of the pyloric region of the stomach with another 8.0 non-absorbable suture, and gently roll two moistened cotton swabs toward each side of the stomach to confirm that the suture is leak-proof. Remove the hemostatic collagen compresses from the abdominal cavity, and return the stomach to its natural position, leaving one hemostatic collagen compress against the suture.
Then use 5.0 non-absorbable sutures to close the muscle layer of the abdominal wall and the skin. For a Roux-en-Y gastric bypass, make a midline skin incision from the sternum to the middle of the abdomen, protecting the skin with a sterile compress soaked with 37 degrees Celsius saline solution. Externalize the intestine, and measure eight centimeters from the pylorus.
Using 5.0 non-absorbable sutures, place two ligatures on the intestine on either side of the eight-centimeter mark, and cut the tissue between the sutures. Then place the proximal limb of the tissue in the upper left quadrant of the abdomen and the distal limb facing the alimentary limb six centimeters below the proximal limb. Using micro scissors, cut both the proximal limb and the intestinal loop, and make two antimesenteric incisions of the same length.
Next, use two 8.0 non-absorbable sutures to make a side-to-side anastomosis, placing the dorsal side anastomosis first, followed by the ventral side anastomosis. Gently roll two moistened cotton swabs toward each side of the anastomosis to confirm that the suture is leak-proof, and carefully externalizing the stomach as just demonstrated. Place a reabsorbable, hemostatic collagen compress behind the organ, and use curved micro forceps to pass a 5.0 non-absorbable suture through the omentum to ligate the pylorus.
Cut the ventral side of the stomach 1.5 centimeters from the pylorus and the distal limb, creating two incisions of the same length, followed by a dorsal to ventral side-to-side anastomosis with two 8.0 non-absorbable sutures. Confirm that the suture does not leak. Then close the muscle layer of the abdominal wall and the skin with 5.0 non-absorbable sutures, and administer 25 milliliters per kilogram of warm saline solution via subcutaneous injection.
When the mouse has fully recovered from the anesthesia, place the animal alone in a cage in 30 degrees Celsius incubator for five days with daily iron and vitamin supplementation and analgesia and free access to gel diet food for the first two days. On the third day after surgery, reintroduce solid food to the animal's diet. A progressive improvement of the post-operative survival rate is observed throughout the protocol, indicating that intensive surgical training is required to master the restrictive malabsorptive bariatric or RYGB surgical technique.
Sleeve gastrectomy and RYGB mice demonstrate a significant weight loss 14 days after surgery compared to sham control animals. The daily food intake of the animals is reduced by over a third during the 14-day period following sleeve gastrectomy, whereas this anorexigenic effect is not observed between the sham and RYGB mice. The animals also exhibit an improved glucose tolerance following both types of surgery.
Further, the severe anemia that is observed in the RYGB mice is improved by iron supplementation up to 28 days after the surgery. Once mastered, these techniques can be completed in less than 50 minutes for the sleeve gastrectomy and 90 minutes for the Roux-en-Y gastric bypass, if they are performed properly. While attempting these procedures, it's important to remember that the pre-and post-operative care procedures are almost as important as the surgical technique.
Following these procedures, other methods, like biliary diversion surgery, can be performed to answer additional questions about the predictive role of bile acids on the effects of bariatric surgery. After the development, these techniques paved the way for researcher in the field of obesity, diabetes, hypertension, and dyslipidemia to expose a mechanism of beneficial metabolite function in wild-type and genetically modified mice. After watching this video, you should have a good understanding of how to perform bariatric surgery in the mouse model.
