CLP surgery

The mouse sepsis model was established as previously described [16] with some modifications. Briefly, animals were anesthetized using intraperitoneal ketamine (80 mg/kg) and xylazine (5 mg/kg). After disinfection, a 2–3-cm incision was made lengthwise below the xiphoid to expose the abdominal cavity. The cecum was isolated and ligated at half the distance between distal pole and the base of the cecum, and punctured twice with a 22-gauge needle (Fig. ​(Fig.2a).2a). Fecal contents were gently extruded into the peritoneal cavity. Then, the cecum was carefully placed back into the abdominal cavity, and the abdomen was sutured. For sham-operated animals, the abdominal cavity was opened to expose the cecum without ligation or perforation. After surgery, 1 ml of sterile saline prewarmed to 37 °C was given intraperitoneally for rehydration. Animals were returned to their cages with a warm cotton pad and free access to food and water. Naïve mice did not undergo laparotomy.

A schematic illustration of CLP procedure and i.c.v. injection. a CLP procedure. The basis of the cecum is indicated by the yellow line. The cecum is ligated (indicated by dotted green line) at half the distance between distal pole and the base of the cecum. b Injection site of the mouse lateral ventricle. The injection site is at 1.0 mm lateral and 0.5 mm posterior to the bregma over the left hemisphere. c A 27 G needle with a 10-μl syringe is used for the injection into the lateral ventricle 2.5-mm deep, perpendicular to the skull surface. Abbreviations: CLP, cecal ligation and perforation; i.c.v., intracerebroventricular