This article details the Roux-en-Y gastric bypass procedure performed on anesthetized mice. The surgery involves creating a Y-shaped intestinal configuration to bypass the normal gastric route, leading to reduced nutrient absorption and weight loss in the subjects.
Begin the Roux-en-Y procedure — a gastric resection surgery — by placing an anesthetized mouse in the supine position. Dissect the abdomen and externalize the small intestine to locate the jejunum — the middle part of the intestine.
Perform two nearby ligations on the jejunum and make an excision between them. This process generates two intestinal limbs — the biliary limb is proximal to the stomach and the alimentary limb is distal to the stomach. Place the biliary limb near the existing intestinal loop. Make equal-sized longitudinal incisions on their antimesenteric surface.
Perform side-to-side anastomosis by suturing incised regions of the biliary limb and the intestinal loop, allowing the gastric juices to enter intestines directly. Locate the stomach and ligate the pylorus — the portion of the stomach that opens into the intestine, which prevents the food from entering the intestine.
Make a new longitudinal incision near the pylorus and the pulled end of the alimentary limb and perform the second side-to-side anastomosis. This new path is called the Roux limb, and the intestine now resembles ‘Y’ shape. Return the ligated organs to the abdominal cavity and suture the incision site.
Post-surgery, the food directly enters from the stomach to the Roux limb, bypassing the normal gastric route. The smaller intestinal length decreases nutrient absorption, causing a reduction in the mouse’s weight.
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 8 centimeters from the pyloris. Using 5-0 non-absorbable sutures, place two ligatures on the intestine on either side of the 8-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, 6 centimeters below the proximal limb. Using micro scissors, cut both the proximal limb and the intestinal loop, and make two anti-mesenteric 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 leakproof, and carefully externalizing the stomach as just demonstrated. Place a re-absorbable hemostatic collagen compress behind the organ, and used 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 5 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.
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