The effects of prucalopride on postoperative ileus in guinea pigs

Inflammation and Impaired Gut Physiology in Post-operative Ileus: Mechanisms and the Treatment Options

Post-operative ileus (POI) is the transient cessation of coordinated gastrointestinal motility after abdominal surgical intervention. It decreases quality of life, prolongs length of hospital stay, and increases socioeconomic costs. The mechanism of POI is complex and multifactorial, and has been broadly categorized into neurogenic and inflammatory phase. Neurogenic phase mediated release of corticotropin-releasing factor (CRF) plays a central role in neuroinflammation, and affects both central autonomic response as well hypothalamic-pituitary-adrenal (HPA) axis. HPA-stress axis associated cortisol release adversely affects gut microbiota and permeability. Peripheral CRF (pCRF) is a key player in stress induced gastric emptying and colonic transit. It functions as a local effector and interacts with the CRF receptors on the mast cell to release chemical mediators of inflammation. Mast cells proteases disrupt epithelial barrier via protease activated receptor-2 (PAR-2). PAR-2 facilitates cytoskeleton contraction to reorient tight junction proteins such as occludin, claudins, junctional adhesion molecule, and zonula occludens-1 to open epithelial barrier junctions. Barrier opening affects the selectivity, and hence permeation of luminal antigens and solutes in the gastrointestinal tract. Translocation of luminal antigens perturbs mucosal immune system to further exacerbate inflammation. Stress induced dysbiosis and decrease in production of short chain fatty acids add to the inflammatory response and barrier disintegration. This review discusses potential mechanisms and factors involved in the pathophysiology of POI with special reference to inflammation and interlinked events such as epithelial barrier dysfunction and dysbiosis. Based on this review, we recommend CRF, mast cells, macrophages, and microbiota could be targeted concurrently for efficient POI management.

Altered Intestinal Permeability and Drug Repositioning in a Post-operative Ileus Guinea Pig Model

Background/Aims

The aim of this study is to identify the alteration in intestinal permeability with regard to the development of post-operative ileus (POI). Moreover, we investigated drug repositioning in the treatment of POI.

Methods

An experimental POI model was developed using guinea pigs. To measure intestinal permeability, harvested intestinal membranes of the ileum and proximal colon was used in an Ussing chamber. To identify the mechanisms associated with altered permeability, we measured leukocyte count and expression of calprotectin, claudin-1, claudin-2, and mast cell tryptase. We compared control, POI, and drug groups (mosapride [0.3 mg/kg and 1 mg/kg, orally], glutamine [500 mg/kg, orally], or ketotifen [1 mg/kg, orally] with regard to these parameters.

Results

Increased permeability after surgery significantly decreased after administration of mosapride, glutamine, or ketotifen. Leukocyte counts increased in the POI group and decreased significantly after administration of mosapride (0.3 mg/kg) in the ileum, and mosapride (0.3 mg/kg and 1 mg/kg), glutamine, or ketotifen in the proximal colon. Increased expression of calprotectin after surgery decreased after administration of mosapride (0.3 mg/kg), glutamine, or ketotifen in the ileum and proximal colon, and mosapride (1 mg/kg) in the ileum. The expression of claudin-1 decreased significantly and that of claudin-2 increased after operation. After administration of glutamine, the expression of both proteins was restored. Finally, mast cell tryptase levels increased in the POI group and decreased significantly after administration of ketotifen.

Conclusions

The alteration in intestinal permeability is one of the factors involved in the pathogenesis of POI. We repositioned 3 drugs (mosapride, glutamine, and ketotifen) as novel therapeutic agents for POI.

Bioelectronics in the brain-gut axis: focus on inflammatory bowel disease (IBD)

Accumulating evidence shows that intestinal homeostasis is mediated by cross-talk between the nervous system, enteric neurons and immune cells, together forming specialized neuroimmune units at distinct anatomical locations within the gut. In this review, we will particularly discuss how the intrinsic and extrinsic neuronal circuitry regulates macrophage function and phenotype in the gut during homeostasis and aberrant inflammation, such as observed in inflammatory bowel disease (IBD). Furthermore, we will provide an overview of basic and translational IBD research using these neuronal circuits as a novel therapeutic tool. Finally, we will highlight the different challenges ahead to make bioelectronic neuromodulation a standard treatment for intestinal immune-mediated diseases.

Inflammation, Impaired Motility, and Permeability in a Guinea Pig Model of Postoperative Ileus

Background/Aims

Postoperative ileus (POI) is characterized by impaired propulsive function of the gastrointestinal tract after surgery. Although inflammation is considered to be an important pathogenesis of POI, significant data are lacking. We aim to correlate the recovery time of postoperative dysmotility with that of inflammation and mucosal permeability.

Methods

An experimental POI model of guinea pig was used. Contractile activity of the circular muscle of the stomach, jejunum, ileum, and proximal colon was measured through a tissue bath study. Inflammatory cells were counted, and the expression of calprotectin and tryptase were analyzed. The expression of protease-activated receptor 2 (PAR-2), claudin-1, and claudin-2 were analyzed with immunofluorescence.

Results

The small bowel and colon showed decreased contractile amplitude in the POI groups compared to control. In contrast to the colon, the contractile amplitude of the small bowel significantly recovered in the POI group at 6 hours after the operation compared to the control group. Inflammation was highly significant in the POI groups compared to the control and sham groups, especially in the colon. Immunofluorescence showed increased PAR-2 expression in the POI groups compared to sham. The decreased claudin-1 expression and increased claudin-2 expression may suggest increased mucosal permeability of the small bowel and colon in the POI groups.

Conclusions

Increased inflammation and mucosal permeability may play an important role in the differential recovery stages in POI. These data may provide further insights into the pathophysiology and potential new therapeutic prospects of POI.

Critical Evaluation of Animal Models of Gastrointestinal Disorders

Preclinical research remains an important tool for discovery and validation of novel therapeutics for gastrointestinal disorders. While in vitro assays can be used to verify receptor-ligand interactions and test for structural activity of new compounds, only whole-animal studies can demonstrate drug efficacy within the gastrointestinal system. Most major gastrointestinal disorders have been modeled in animals; however the translational relevance of each model is not equal. The purpose of this chapter is to provide a critical evaluation of common animal models that are being used to develop pharmaceuticals for gastrointestinal disorders. For brevity, the models are presented for upper gastrointestinal disorders involving the esophagus, stomach, and small intestine and lower gastrointestinal disorders that focus on the colon. Particular emphasis is used to explain the face and construct validity of each model, and the limitations of each model, including data interpretation, are highlighted. This chapter does not evaluate models that rely on surgical or other non-pharmacological interventions for treatment.

YH12852, a potent and highly selective 5-HT4 receptor agonist, significantly improves both upper and lower gastrointestinal motility in a guinea pig model of postoperative ileus

BACKGROUND

Postoperative ileus (POI) is a transient gastrointestinal (GI) dysmotility that commonly develops after abdominal surgery. YH12852, a novel, potent and highly selective 5-hydroxytryptamine 4 (5-HT₄ ) receptor agonist, has been shown to improve both upper and lower GI motility in various animal studies and may have applications for the treatment of POI. Here, we investigated the effects and mechanism of action of YH12852 in a guinea pig model of POI to explore its therapeutic potential.

METHODS

The guinea pig model of POI was created by laparotomy, evisceration, and gentle manipulation of the cecum for 60 seconds, followed by closure with sutures under anesthesia. Group 1 received an oral administration of vehicle or YH12852 (1, 3, 10 or 30 mg/kg) only, while POI Group 2 was intraperitoneally pretreated with vehicle or 5-HT₄ receptor antagonist GR113808 (10 mg/kg) prior to oral dosing of vehicle or YH12852 (3 or 10 mg/kg). Upper GI transit was evaluated by assessing the migration of a charcoal mixture in the small intestine, while lower GI transit was assessed via measurement of fecal pellet output (FPO).

KEY RESULTS

YH12852 significantly accelerated upper and lower GI transit at the doses of 3, 10, and 30 mg/kg and reached its maximal effect at 10 mg/kg. These effects were significantly blocked by pretreatment of GR113808 10 mg/kg.

CONCLUSION AND INFERENCES

Oral administration of YH12852 significantly accelerates and restores delayed upper and lower GI transit in a guinea pig model of POI. This drug may serve as a useful candidate for the treatment of postoperative ileus.

Evidence-Based Advances in Rodent Medicine

The number of exotic companion pet rodents seen in veterinary practices is growing very rapidly. According to the American Veterinary Medical Association's surveys, more than 2,093,000 pet rodents were kept in US households in 2007 and in 2012 it was more than 2,349,000 animals. This article summarizes the most important evidence-based knowledge in exotic pet rodents (diagnostics of the hyperadrenocorticism in guinea pigs, pituitary tumors in rats, urolithiasis in guinea pigs, use of itopride as prokinetics, use of deslorelin acetate in rodents, cause of dental disease, and prevention of mammary gland tumors in rats).

Tracking gastrointestinal transit of solids in aged rats as pharmacological models of chronic dysmotility

BACKGROUND

Dysmotility in the gastrointestinal (GI) tract often leads to impaired transit of luminal contents leading to symptoms of diarrhea or constipation. The aim of this research was to develop a technique using high resolution X-ray imaging to study pharmacologically induced aged rat models of chronic GI dysmotility that mimic accelerated transit (diarrhea) or constipation. The 5-hydroxytryptamine type 4 (5-HT4 ) receptor agonist prucalopride was used to accelerate transit, and the opioid agonist loperamide was used to delay transit.

METHODS

Male rats (18 months) were given 0, 1, 2, or 4 mg/kg/day prucalopride or loperamide (in dimethyl sulfoxide, DMSO) for 7 days by continuous 7-day dosing. To determine the GI region-specific effect, transit of six metallic beads was tracked over 12 h using high resolution X-ray imaging. An established rating scale was used to classify GI bead location in vivo and the distance beads had propagated from the caecum was confirmed postmortem.

KEY RESULTS

Loperamide (1 mg/kg) slowed stomach emptying and GI transit at 9 and 12 h. Prucalopride (4 mg/kg) did not significantly alter GI transit scores, but at a dose of 4 mg/kg beads had moved significantly more distal than the caecum in 12 h compared to controls.

CONCLUSIONS & INFERENCES

We report a novel high-resolution, non-invasive, X-ray imaging technique that provides new insights into GI transit rates in live rats. The results demonstrate that loperamide slowed overall transit in aged rats, while prucalopride increased stomach emptying and accelerates colonic transit.

Randomised clinical trial: prucalopride, a colonic pro-motility agent, reduces the duration of post-operative ileus after elective gastrointestinal surgery

BACKGROUND

Previous studies have shown that recovery of colonic transit is a major determinant of post-operative ileus and clinical recovery after gastrointestinal surgery. Prucalopride is a highly selective 5-hydroxytryptamine receptor-4 agonist with colonic pro-motility effects.

AIM

To evaluate the effect and safety of prucalopride on post-operative ileus and surgical outcomes after elective gastrointestinal surgery.

METHODS

In this phase II randomised clinical trial, 110 patients undergoing elective gastrointestinal surgery were randomised to either oral prucalopride (2 mg/day) (n = 55) or placebo (n = 55). Intervention was started 24 h after surgery and stopped after defecation or maximally at 7 days. The primary outcome was time to defecation. Secondary outcomes included time to first passage of flatus, tolerance of solid food, nasogastric tube reinsertion, post-operative length of stay, hospital readmission, overall cost, time to walk independently, surgical complications and inflammatory parameters.

RESULTS

Patients who received prucalopride had a shorter time to defecation (65.0 vs. 94.5 h, P = 0.001), passage of flatus (53.0 vs. 73.0 h, P < 0.001), and post-operative length of stay (7.0 vs. 8.0 days, P = 0.001) than controls. The number of patients with prolonged ileus (>5 days) (16.4% vs. 34.5%, P = 0.026) and the C-reactive protein level on post-operative day 5 (35.67 vs. 59.07 mg/L, P = 0.040) were lower in the prucalopride group. There was no significant difference in post-operative Clavien-Dindo grade III and IV complications (P = 0.606) between the groups.

CONCLUSION

Prucalopride is a safe and effective treatment to reduce post-operative ileus and systemic inflammation without affecting post-operative complications in patients undergoing elective gastrointestinal surgery. ClinicalTrials.gov: NCT02004652.

Alteration of enteric monoamines with monoamine receptors and colonic dysmotility in 6-hydroxydopamine-induced Parkinson's disease rats

Constipation is common in Parkinson's disease (PD), in which monoamines (dopamine [DA], norepinephrine [NE], and 5-hydroxytryptamine [5-HT]) play an important role. Rats microinjected with 6-hydroxydopamine (6-OHDA) into the bilateral substantia nigra (SN) exhibit constipation, but the role of monoamines and their receptors is not clear. In the present study, colonic motility, monoamine content, and the expression of monoamine receptors were examined using strain gauge force transducers, ultraperformance liquid chromatography tandem mass spectrometry, immunofluorescence, and Western blot. The 6-OHDA rats displayed a significant reduction in dopaminergic neurons in the SN and a decreased time on rota-rod test and a marked decrease in daily fecal production and fecal water content. The amplitude of colonic spontaneous contraction was obviously decreased in 6-OHDA rats. Blocking D1-like receptor and β3-adrenoceptor (β3-AR) significantly reduced the inhibition of DA and NE on the colonic motility, respectively, whereas the 5-HT and 5-HT4 receptor agonists promoted the colonic motility. Moreover, DA content was increased in the colonic muscularis externa of 6-OHDA rats. The protein expression of β3-ARs was notably upregulated, but 5-HT4 receptors were significantly decreased in the colonic muscularis externa of 6-OHDA rats. We conclude that enhanced DA and β3-ARs and decreased 5-HT4 receptors may be contributed to the colonic dysmotility and constipation observed in 6-OHDA rats.