The chief target of the surgical intervention is to measure the metabolic effects and the insulin resistance of sleeve gastrectomy in a more assessable mouse model. This protocol aims to produce an animal model for the research of the mechanisms that underline the results seen after a bariatric surgery in humans, which may provide insights into the pathogenesis of obesity and type 2 diabetes treatment. For sleeve gastrectomy and sham operation, after confirming the appropriate depth of anesthesia by toe stimulation, apply the Carbomer 0.2%eye gel on the mouse's eyes to prevent dry eyes.
The mouse is placed and fixed on the surgical table. Remove and clean the remaining hair with a depilatory cream. Disinfect the abdomen of the mouse with povidone-iodine solutions alternating with alcohol for three applications.
Perform the SG procedure with the aid of a magnifying dissecting microscope or magnifier as necessary to prevent any unpredictable bleeding and hypovolemic shock. Make a one to 1.5 centimeters in length midline incision at the upper abdomen. Use two curved smooth serrated micro-forceps to gently move the stomach and complete externalize it.
Move the intestine to the bare skin on the side and cover it with warm saline moistened gauze to prevent dehydration. Carefully divide the gastrosplenic ligament connecting the left stomach to the spleen using a cotton-tipped probe and electrocautery as needed, thereby dissecting the gastric fundus from the surrounding spleen and other internal organs. Stretch the fundus and pylorus of the stomach gently and laterally with forceps, identify the midline of the stomach and carefully apply two surgical clips using the LIGACLIP applier to the 15%medial segment of the stomach from the gastroesophageal junction inferiorly and pylorus superiorly.
Clamp and isolate around 75-80%of stomach, thereby creating the entire lateral sleeve of the stomach. Resect the lateral isolated stomach with a microscissors. Use cotton swabs to remove any residual food from the stomach and then clean the cut edge of the stomach with povidone-iodine aqueous solution.
Oversew the clip line with a 5-0 monofilament nonabsorbable suture to make sure of no leakage. Knot the ends of the suture and anchor to the clips on either end. Return the stomach and intestine to the proper position in the abdominal cavity and close the abdomen with a running 5-0 monofilament nonabsorbable suture to the abdominal wall.
For sham procedure of SG, perform a similar procedure as described previously with a midline laparotomy, externalize the intestine and stomach using 37 degree Celsius wet warm saline gauze coverage for five minutes. Return the stomach and intestine to the proper sites of these internal organs. Administer ketoprofen two to five milligrams per kilogram and cefazolin 25 milligrams per kilogram subcutaneously or intraperitoneally after surgery for the pain control and infection prevention.
Stop the isoflurane and continuing with a room air flow of three to five liters per minute until the mouse is fully awake. Keep watching the mouse while it regains mobility and begins to walk around the cage. Place the mouse in the independent incubator around 30 degrees Celsius in temperature condition for five days, making sure there is only one mouse per cage.
In our experienced hands, the successful rate of SG was around 90%after the learning period. The body weight of sham operated and high-fat diet fed mice gained steadily. But the sleeve gastrectomy and high-fat diet fed mice decreased continuously.
The difference of the cholesterol level was significant between the high-fat diet fed mice with sham and sleeve gastrectomy. This might indicate that oxidative stress improvement after the sleeve gastrectomy. The difference of the levels of hemoglobin A1C and IPGTT were significant as well.
Between the high-fat diet fed mice with sham and sleeve gastrectomy and by indicating insulin-resistance and sugar control improvement after the sleeve gastrectomy. This animal model can help us to investigate the clinical relevance of diabetes and obesity in using a brief surgical procedure with sleeve gastrectomy. This procedure can shorten the operation time and improve the surgical survival rate.
The main advantage of this study is to imitate the clinical outcomes of bariatric surgery in human patients using a simple surgical mouse model.
