Ghrelin and ghrelin mimetics stimulate appetite and enhance gastric motility. The present study investigates whether ipamorelin, a selective growth hormone secretagogue and agonist of the ghrelin receptor, would accelerate gastrointestinal transit and ameliorate the symptoms in a rodent model of postoperative ileus (POI). Fasted male rats were subjected to laparotomy and intestinal manipulation. At the end of surgery, a dye marker was infused in the proximal colon to evaluate postsurgical colonic transit time, which was the time to the first bowel movement. In addition, fecal pellet output, food intake, and body weight were monitored regularly for 48 h. Ipamorelin (0.01-1 mg/kg), growth hormone-releasing peptide (GHRP)-6 (20 g/kg), or vehicle (saline) were administered via intravenous bolus infusion after a single dosing or a 2-day repetitive dosing regimen (four doses a day at 3-h intervals). Compared with the vehicle, a single dose of ipamorelin (1 mg/kg) or GHRP-6 (20 g/kg) decreased the time to the first bowel movement but had no effect on cumulative fecal output, food intake, or body weight gain measured 48 h after the surgery. In contrast, repetitive dosing of ipamorelin (0.1 or 1 mg/kg) significantly increased the cumulative fecal pellet output, food intake, and body weight gain. The results suggest that postsurgical intravenous infusions of ipamorelin may ameliorate the symptoms in patients with POI.Postoperative ileus (POI) is a gastrointestinal (GI) dysfunction that develops as a consequence of abdominal surgery or other major surgical procedures. Abdominal distention, nausea, vomiting, anorexia, and an inability to pass stool are the main symptoms of POI. Although normal GI motility returns spontaneously within several days in most patients, POI is the main cause for prolonged hospitalization and often leads to serious complications in others (Senagore, 2007). The mechanisms causing POI are complex, involving immune and neuronal reactions to the surgery that result in delayed gastric emptying and impaired propulsive motility of the bowel (Bauer and Boeckxstaens, 2004). In addition, opioid drugs used for pain management contribute significantly to the delay in GI transit.POI is a generalized event involving the entire GI tract and not restricted to the region directly subjected to manipulation. Manipulation of the small intestine in the rat was found to inhibit muscle contractility and evoke inflammatory responses in the stomach and the colon (Kalff et al., 1998;Schwarz et al., 2004), whereas manipulation of the cecum delayed gastric emptying (Martínez et al., 1999). Moreover, the time course of functional recovery varies in different anatomical regions of the GI tract. In humans, small intestinal motility recovers within several hours, whereas the recovery of gastric function takes 1 to 2 days, and colonic propulsive motility requires at least 2 to 3 days for recovery (Condon et al., 1986). There are currently no pharmacological agents available to normalize gut motility, and the pharmacologic...