Vasoactive intestinal peptide and substance P receptor antagonists improve postoperative ileus

Postoperative bowel complications after non-shunt-related neurosurgical procedures: case series and review of the literature

Postoperative bowel complications after non-shunt-related neurosurgical procedures are relatively rare. In an effort to identify the primary risk factors, we evaluated postoperative bowel complications in cranial, endovascular, and spinal procedures in neurosurgery patients using our own institutional case series along with a literature review.We identified severe postoperative bowel complications that occurred at our institution after non-shunt-related neurosurgical procedures between July 2016 and December 2018. We also completed a systematic review of PubMed/MEDLINE using search terms related to bowel complications.At our institution, 7 patients (average age 49.7 ± 9.5 years, range 34-60; no apparent sex predilection) had severe postoperative bowel complications after undergoing a total of 10 neurosurgical procedures. Diagnosis was on average 1 week postoperatively (range 5-13 days), and the time between radiographic/clinical diagnosis and either surgery or death was 1.3 ± 1.4 days (range 0-4 days). Bowel perforation occurred in 4 patients. Five of the patients died, 3 as a direct result of the bowel complication. In the literature review, we identified 6487 spine and 66 cranial and/or endovascular bowel complications after neurosurgical procedures.Our case series and literature review demonstrate that severe postoperative bowel complications after non-shunt-related neurosurgical procedures, while rare, carry significant morbidity/mortality despite prompt and aggressive management. These can also happen without direct injury to bowel tissue, instead occurring as sequelae of inflammatory processes, as well as from delayed mobility, extended use of opiate narcotics, and lack of standardized protocols to ensure early bowel movements that likely stems from unfamiliarity with this potentially devastating complication.

Incidence and Risk of Severe Ileus After Orthopedic Surgery: A Case-Control Study

BACKGROUND

Post-operative ileus (POI) is common and can be associated with significant morbidity.

QUESTIONS/PURPOSES

We aimed to identify the incidence of and risk factors associated with severe post-operative ileus (SPOI) after elective orthopedic surgery.

METHODS

We conducted a retrospective case-control study of patients undergoing elective orthopedic procedures at a single musculoskeletal specialty hospital. SPOI cases matched 1:2 to non-POI controls. International Classification of Diseases, Ninth Revision (ICD-9), codes were used to identify patients who were coded as having an episode of POI. After chart review, a subset was classified as clinical SPOI cases, based on set criteria. Regression models were constructed to identify variables associated with SPOI.

RESULTS

Of 273 POI cases, 77 (28.2%) were classified as SPOI. Overall rates of SPOI were 2.74/1000 orthopedic discharges, with SPOI most common in spine surgeries (9.07/1000 spine procedure discharges). Hypothesis-generating multivariable conditional logistic regression suggested that, for hip and knee cases, not being on a full diet by post-operative day (POD) 2 posed an increased risk of SPOI. For spine cases, not being on a full diet on POD 2 and longer surgery times were associated with risk of SPOI.

CONCLUSIONS

In this retrospective case-control study, patients undergoing elective orthopedic procedures who had not progressed to full diet by POD 2 and spine patients with longer operative times were most at risk for SPOI. These data can be used clinically by peri-operative physicians to stratify patients according to risk.

Tachykinin antagonists ameliorate surgically induced impairment of gastrointestinal motility in rats

The protective effects of tachykinin receptor antagonists: SR140333 (NK₁ receptor), SR48968 (NK₂ receptor), and SB222200 (NK₃ receptor) were tested in rats against a surgically induced postoperative inhibition of gut motility, a common complication of abdominal surgery. The small intestinal transit of Evans blue was measured 24-h post-surgery in untreated rats and animals subjected to skin incision, laparotomy, or laparotomy followed by gut evisceration and manipulation. Surgical procedures were conducted under diethyl ether anesthesia. In comparison to untreated and ether-anesthetized rats, animals undergoing skin incision, laparotomy, or laparotomy with gut evisceration and manipulation showed a significant decrease in the intestinal transit of Evans blue. The pretreatment with NK₁ (3-100 µg/kg), NK₂ (3-30 µg/kg), and NK₃ (10-300 µg/kg) blockers before surgery ameliorated the inhibitory effects of gut manipulation in a dose-dependent manner. Moreover, the submaximal and maximal doses of NK₃ antagonists showed a trend toward reversing not only the inhibition caused by gut manipulation but also laparotomy. An additive effect of combining submaximal doses of NK_1-3 blockers was observed in animals pretreated with NK₁  + NK₂ compared to single-agent NK₁ and NK₂ . Additionally, doublets: NK₁  + NK₃ or NK₂  + NK₃ and a triplet: NK₁  + NK₂  + NK₃ proved to be more effective than NK₂ antagonist alone. In contrast, NK_1-3 blockers have not markedly affected the intestinal propulsion in untreated rats or animals subjected to skin incision or laparotomy. NK_1-3 blockers ameliorated the suppressed small-bowel gut motility 24 post-surgery. Combined pretreatment with NK_1-3 antagonists provided selective, additive benefits compared to single agents.

[Does chewing gum improve postoperative results in patients undergoing radical cystectomy? A systematic review of literature and meta-analysis]

INTRODUCTION

Postoperative ileus occurs in different degrees, in the majority of patients undergoing radical cystectomy, which may increase the length of hospital stay. The use of chewing gum has demonstrated its effectiveness in reducing time-to-bowel function and the length of hospital stay in several surgical procedures.

OBJECTIVE

To evaluate the benefit of post-operative chewing gum use in patients undergoing radical cystectomy through a systematic review of the literature and meta-analysis.

MATERIAL AND METHODS

We performed a literature search of MedLine, Scopus, CochraneLibrary and ClinicalTrials.Gov in March 2017 according to the Cochrane Handbook and the Preferred Reporting Items for Systematic Reviews and Meta-Analyzes. The studies were evaluated according to the "Oxford Center for Evidence-Based Medicine" criteria. The outcome measures evaluated were time-to-flatus, time-to-defecation, length of the hospital stay, and the rates of general and gastrointestinal postoperative complications. Continuous and dichotomous variables were compared respectively using weighted means differences and odds ratios with 95 % confidence intervals. The presence of publication bias was examined by funnel plots.

RESULTS

Three studies (including 274 patients in total) met the inclusion criteria. The pooled results demonstrated a 11.82hour reduction in time-to-flatus (95 % CI : -15.43, -8.22h, P <0.00001), and 19.57hours in time-to-defecation (95 % CI : -29.33, -9.81h, P <0.0001), and a decreasing trend of 2.85 days in the length of the hospital stay (95 % CI : -6.13, -0.43, P=0.09), by the use of chewing gum. There was no significant difference between the "chewing gum" and "control" groups in terms of general and gastrointestinal complications (Peto Odds ratio 1.04 [0.60, 1.79], 95 % CI, P=0.89 and Peto Odds ratio 0.65 [0.26, 1.61], 95 % CI, P=0.35 respectively).

CONCLUSION

Chewing gum may be recommended postoperatively in patients undergoing radical cystectomy to improve time-to-bowel function.

Nomogram-Derived Prediction of Postoperative Ileus after Colectomy: An Assessment from Nationwide Procedure-Targeted Cohort

Postoperative ileus (POI) is a clinical burden to health-care system. This study aims to evaluate the incidence and predictors of POI in patients undergoing colectomy and create a nomogram by using recently released procedure-targeted nationwide database. Patients who underwent elective colectomy in 2012 and 2013 were identified from American College of Surgeons National Surgical Quality Improvement Program using the new procedure-targeted database. Demographics, comorbidities, and 30-day postoperative outcomes were evaluated. Variables in the final step-wise multiple logistic regression model for each outcome were selected in a stepwise fashion using Akaike's information criterion. A nomogram was created to aid in the calculation of POI risk for individual patients. A total of 29,201 patients met the inclusion criteria; 3834 (13.1%) developed POI with a male predominance (55.9%). Patients who developed ileus had longer length of hospital stay (11 vs 5 days; P < 0.001) and operative time (200 vs 174 minutes; P < 0.001). In the stepwise logistic regression model, the following variables were found to be independent risk factors for POI: older age (P < 0.001), male gender (P < 0.001), American Society of Anesthesiologists class III/IV (P < 0.001), open approach (P < 0.001), preoperative septic conditions (P < 0.001), omission of oral antibiotic before surgery (P < 0.001), right colectomy or total colectomy vs other procedures (P < 0.001), smoking (P = 0.001), decreased preoperative serum albumin level (P < 0.001), and prolonged operating time (P < 0.001). All postoperative complications were more frequently occurred in patients with POI. The nomogram accurately predicted POI with a concordant index for this model of 0.69. The use of minimal invasive techniques, control of preoperative septic conditions, oral antibiotic bowel preparation and shorter operative time are associated with a decreased rate of POI. External validation is essential for the confirmation and further evaluation of our logistic regression model and nomogram.

[Evaluation of clinical efficacy of serotonin adipate in treatment and prevention of enteral insufficiency syndrome at generalized peritonitis]

AIM

To substantiate pathogenetic expediency and to evaluate the clinical efficacy of the drug use serotonin adipate (dinaton) in a complex correction enteral insufficiency syndrome (EIN) in patients with generalized peritonitis (GP).

MATERIAL AND METHODS

The comparative analysis of results of treatment of 182 patients with GP, which in principle approach to EIN correction in the postoperative period were divided into two groups. Group I consisted of 92 patients who received standard intensive therapy using conventional methods of stimulation of intestinal peristalsis. Group II consisted of 90 patients on a background of standard treatment was carried further pharmacological stimulation of intestinal motility drug serotonin adipate (dinaton). The research program included an assessment of clinical parameters intestinal motility recovery, evaluation of the severity of the patients on a scale of APACHE II, determining the blood levels of serotonin and the level of the main biomarkers of systemic inflammatory response (SIR), the study of blood flow in the vessels of splanchnic bed, the measurement of intra-abdominal pressure with the calculation of intraperitoneal perfusion pressure.

RESULTS

It is found that the development and progression of abdominal inflammation is accompanied by a sharp decrease in blood serotonin level is in phase III GP decreases 4.7 times compared to the control value. It is shown that using of serotonin adipate (dinaton) in treatment of patients with GP promotes early recovery of intestinal motility and the resolution of EIN, the elimination of intra-abdominal hypertension and disorders of splanchnic blood flow, as well as the rapid regression of the manifestations of the SIR and endotoxemia. Postoperative mortality in group I patients was 28.3% in group II - 20.0%.

CONCLUSION

The inclusion of serotonin adipate (dinaton) in the complex corrective therapy standard in the postoperative period in GP patients is pathogenetically justified, as it promotes early restoration of motor activity of the gastrointestinal tract, the elimination of intestinal paresis and resolution of EIN, which leads to an improvement of results of surgical treatment of this patients.

Xylitol Gum Chewing to Achieve Early Postoperative Restoration of Bowel Motility After Laparoscopic Surgery

Our objective was to evaluate the effects of postoperative xylitol gum chewing on gastrointestinal functional recovery after laparoscopy. Altogether, 120 patients undergoing elective gynecologic laparoscopy were randomly divided into 2 groups of 60 each (final numbers: 53 controls, 56 patients). Controls underwent a routine postoperative regimen. Starting 6 hour after surgery, study patients chewed mint-flavored, sugarless xylitol gum until flatus occurred thrice a day. Other postoperative management was routine. First bowel sounds, first flatus, first bowel movement, and discharge times were recorded. Symptoms included abdominal distension, nausea, and vomiting. First flatus and first bowel sounds occurred significantly (P<0.001) earlier in the study patients. No significant differences were found for first defecation time, hospitalization duration, or mild/severe intestinal obstruction (all P>0.05). Thus, xylitol gum chewing after laparoscopy can effectively shorten the time to first flatus and helps with postoperative gastrointestinal functional recovery. It is simple, convenient, and well tolerated.

The novel CGRP receptor antagonist BIBN4096BS alleviates a postoperative intestinal inflammation and prevents postoperative ileus

BACKGROUND

Abdominal surgery results in neuronal mediator release and subsequent acute intestinal hypomotility. This phase is followed by a longer lasting inflammatory phase resulting in postoperative ileus (POI). Calcitonin gene-related peptide (CGRP) has been shown to induce motility disturbances and in addition may be a candidate mediator to elicit neurogenic inflammation. We hypothesized that CGRP contributes to intestinal inflammation and POI.

METHODS

The effect of CGRP in POI was tested in mice treated with the highly specific CGRP receptor antagonist BIBN4096BS and in CGRP receptor-deficient (RAMP-1(-/-) ) mice. POI severity was analyzed by cytokine expression, muscular inflammation and gastrointestinal (GI) transit. Peritoneal and muscularis macrophages and mast cells were analyzed for CGRP receptor expression and functional response to CGRP stimulation.

KEY RESULTS

Intestinal manipulation (IM) resulted in CGRP release from myenteric nerves, and a concurrent increased interleukin (IL)-6 and IL-1β transcription and leukocyte infiltration in the muscularis externa and increased GI transit time. CGRP potentiates IM-induced cytokine transcription within the muscularis externa and peritoneal macrophages. BIBN4096BS reduced cytokine levels and leukocyte infiltration and normalized GI transit. RAMP1(-/-) mice showed a significantly reduced leukocyte influx. CGRP receptor was expressed in muscularis and peritoneal macrophages but not mast cells. CGRP mediated macrophage activation but failed to induce mast cell degranulation and cytokine expression.

CONCLUSIONS & INFERENCES

CGRP is immediately released during abdominal surgery and induces a neurogenic inflammation via activation of abdominal macrophages. BIBN4096BS prevented IM-induced inflammation and restored GI motility. These findings suggest that CGRP receptor antagonism could be instrumental in the prevention of POI.

Risk factors for prolonged ileus following colon surgery

BACKGROUND

Prolonged ileus is one of the most common postoperative complications after colorectal surgery. We sought to investigate the predictors of prolonged ileus following elective colon resections procedures.

METHODS

The national participant user files of NSQIP databases were utilized to examine the clinical outcomes of patients undergoing elective colon resection during 2012-2013. Multivariate regression analysis was performed to investigate predictors of prolonged ileus. Prolonged ileus was defined as no return of bowel function in 7 days.

RESULTS

We sampled a total of 27,560 patients who underwent colon resections; of these, 3497 (12.7%) patients had prolonged ileus. Patients with ileocolonic anastomosis (ICA) had a significantly higher rate of prolonged ileus compared to patients with colorectal anastomosis (CRA) (15 vs. 11.5%, AOR 1.25, P < 0.01). Prolonged ileus was significantly associated with intra-abdominal infections (13 vs. 2.8%, AOR 2.56, P < 0.01) and anastomotic leakage (12 vs. 2.4%, AOR 2.50, P < 0.01). Factors such as preoperative sepsis (AOR 1.63, P < 0.01), disseminated cancer (AOR 1.24, P = 0.01), and chronic obstructive pulmonary disease (AOR 1.27, P = 0.02) were associated with an increased risk of prolonged ileus, whereas oral antibiotic bowel preparation (AOR 0.77, P < 0.01) and laparoscopic surgery (AOR 0.51, P < 0.01) are associated with decreased prolonged ileus risk.

CONCLUSIONS

Prolonged ileus is a common condition following colon resection, with an incidence of 12.7%. Among colon surgeries, colectomy with ICA resulted in the highest rate of postoperative prolonged ileus. Prolonged ileus is positively associated with anastomotic leak and intra-abdominal infections; thus, a high index of suspicion must be had in all patients with prolonged postoperative ileus.

Postoperative ileus: mechanisms and future directions for research

Postoperative ileus (POI) is an abnormal pattern of gastrointestinal motility characterized by nausea, vomiting, abdominal distension and/or delayed passage of flatus or stool, which may occur following surgery. Postoperative ileus slows recovery, increases the risk of developing postoperative complications and confers a significant financial load on healthcare institutions. The aim of the present review is to provide a succinct overview of the clinical features and pathophysiological mechanisms of POI, with final comment on selected directions for future research.Terminology used when describing POI is inconsistent, with little differentiation made between the obligatory period of gut dysfunction seen after surgery ('normal POI') and the more clinically and pathologically significant entity of a 'prolonged POI'. Both normal and prolonged POI represent a fundamentally similar pathophysiological phenomenon. The aetiology of POI is postulated to be multifactorial, with principal mediators being inflammatory cell activation, autonomic dysfunction (both primarily and as part of the surgical stress response), agonism at gut opioid receptors, modulation of gastrointestinal hormone activity and electrolyte derangements. A final common pathway for these effectors is impaired contractility and motility and gut wall oedema. There are many potential directions for future research. In particular, there remains scope to accurately characterize the gastrointestinal dysfunction that underscores an ileus, development of an accurate risk stratification tool will facilitate early implementation of preventive measures and clinical appraisal of novel therapeutic strategies that target individual pathways in the pathogenesis of ileus warrant further investigation.

Incidence and risk factors for postoperative ileus following anterior, posterior, and circumferential lumbar fusion

BACKGROUND CONTEXT

Postoperative ileus is a known complication of surgery. The incidence and risk factors for ileus after lumbar fusion surgery is not well characterized.

PURPOSE

To determine rates of postoperative ileus, a population-based database was analyzed to identify incidence, mortality, and risk factors associated with anterior (ALF), posterior (PLF), and combined anterior/posterior (APLF) lumbar fusions.

STUDY DESIGN

This was a retrospective database analysis.

PATIENT SAMPLE

The sample consisted of 220,522 patients from the Nationwide Inpatient Sample (NIS) database.

OUTCOME MEASURES

Outcome measures were incidence of postoperative ileus, length of stay (LOS), in-hospital costs, and mortality.

METHODS

Data from the NIS were obtained from 2002 to 2009. Patients undergoing ALF, PLF, and APLF for degenerative pathologies were identified and the incidence of postoperative ileus was assessed. Patient demographics, Charlson comorbidity index (CCI), LOS, costs, and mortality were assessed. SPSS v.20 was used to detect statistical differences between groups and perform logistic regression analyses to identify independent predictors of postoperative ileus. A p value less than .001 denoted significance.

RESULTS

A total of 220,522 lumbar fusions were identified in the United States from 2002 to 2009. There were 19,762 ALFs, 182,801 PLFs, and 17,959 APLFs. The incidence of postoperative ileus was increased in ALFs over PLFs (74.9 vs. 26.0 per 1,000; p<.001). Within PLF and APLF groups, CCI scores were increased in the presence of postoperative ileus (p<.001). Across cohorts, patients with postoperative ileus demonstrated greater LOS and costs (p<.001). PLF-treated patients with postoperative ileus demonstrated increased mortality (p<.001). Independent predictors of postoperative ileus included male gender, 3+ fusion levels, alcohol abuse, anemia, fluid/electrolyte disorders, and weight loss (p<.001).

CONCLUSIONS

The results of our study demonstrate increased incidence of postoperative ileus associated with anterior approaches for lumbar fusion. Across cohorts, postoperative ileus was associated with increased LOS and costs. To determine the mortality and resource use associated with postoperative ileus, we recommend preoperatively identifying and treating modifiable risk factors, especially when an anterior approach is used.

Facilitating return of bowel function after colorectal surgery: alvimopan and gum chewing

Postoperative ileus is common after colorectal surgery, and has a huge impact on hospital LOS. With the impeding cost crisis in the United States, safely reducing length of stay is essential. Chewing gum and pharmacological treatment with alvimopan are safe, simple tools to reduce postoperative ileus and its associated costs. Future research will determine if integrating these tools with laparoscopic procedures and enhanced recovery pathways is a best practice in colorectal surgery.

Changes in peptidergic neurotransmission during postoperative ileus in rat circular jejunal muscle

BACKGROUND

Our aim was to explore unknown changes in neurotransmission with vasoactive intestinal peptide (VIP) and Substance P (Sub P) during postoperative ileus (POI).

METHODS

Contractile activity of rat circular jejunal muscle strips was studied in five groups (n = 6/group): Naïve controls, sham controls 12 h and 3 days after laparotomy, and rats 12 h, 3 days after induction of POI. Dose-responses to VIP (10(-10) -10(-7) M), Sub P (3 × 10(-10) -3 × 10(-7) M), and electrical field stimulation (EFS, to study endogenous release of neurotransmitters) were studied with different antagonists. Intestinal transit, inflammatory cells and immunoreactivity for VIP and Sub P were investigated in the bowel wall and cellular Finkel osteo sarcoma expression was determined in vagal afferent and efferent nuclei of the brainstem.

KEY RESULTS

Postoperative ileus characterized by delayed intestinal transit and intramural inflammation was associated with an increased inhibitory effect of VIP on contractile activity. A biphasic impact was observed for Sub P with a decrease in its excitatory potential on contractility at 12 h, followed by a later increase 3 days postoperatively. Inhibitory response to EFS was increased, whereas the excitatory response decreased in ileus animals. VIP expression was increased in all postoperative animals while only animals 3 days after ileus induction showed increased Sub P expression in the myenteric plexus. These changes were associated with an activation of afferent but not efferent vagal nuclei in the brain stem.

CONCLUSIONS & INFERENCES

Specific, time-dependent changes in peptidergic neurotransmission with VIP and Sub P occur during POI that are associated with vagal afferent activation, but are independent of the activation of efferent vagal pathways.

Sham feeding with chewing gum after elective colorectal resectional surgery: a randomized clinical trial

OBJECTIVE

To determine whether sham feeding with chewing gum improved gastrointestinal recovery after colorectal resection surgery, in the presence of routine postoperative feeding.

BACKGROUND

Sham feeding with chewing gum has been shown to accelerate the return of gut function after colorectal surgery. This study sought to determine whether sham feeding with gum, after colorectal resection, accelerates return of gastrointestinal function in patients on a rapid feeding enhanced recovery program.

METHODS

A randomized "two armed" controlled clinical trial was performed. Equal groups of open and laparoscopic colorectal resection surgical patients were recruited. Patients in the intervention arm received chewing gum 4 times a day postoperatively. All patients in the trial were placed on an established, standardized Enhanced Recovery After Surgery program. The primary outcome was time to return of gut function, assessed by time to flatus and first bowel motion. Secondary outcomes were time to tolerate diet, symptoms of ileus in the form of nausea, vomiting and distension, pain as assessed by analgesic consumption and visual analogue scales, complications, and length of hospital stay.

RESULTS

A total of 161 patients were recruited. Postoperative morbidity was equivalent between groups, with no complications related to gum chewing. There was no difference between groups with respect to the primary outcomes of time to flatus and bowel motion. There was less perception of pain in the intervention group on days 2 to 5, and no difference with respect to all other secondary outcomes.

CONCLUSIONS

Sham feeding with gum, after open and laparoscopic colorectal resectional surgery is safe, but does not hasten the return of gastrointestinal function in patients who receive accelerated postoperative feeding. (ACTRN12607000538448).

T-helper cell type 1 memory cells and postoperative ileus in the entire gut

PURPOSE OF REVIEW

The pathophysiological riddle of the clinically important postoperative ileus (POI) has been solved more and more over the last decade. The POI is caused by inflammation and paralysis at the manipulated site propagating to the entire, unmanipulated gastrointestinal tract. Intestinal macrophages produce mediators that paralyze myocytes, but it is unclear how macrophages are activated, particularly those in unmanipulated areas. In addition to direct or neurally mediated activation of intestinal macrophages, a new immunologically mediated activation has been proposed.

RECENT FINDINGS

Recently, it has been shown that the surgical trauma induces interleukin-12 (IL-12) production by intestinal dendritic cells, which activates TH1-memory cells at the manipulated site. Those TH1-memory cells produce interferon-γ (IFN-γ). Those TH1 CCR9 cells also migrate to unmanipulated parts of the gastrointestinal tract. Their IFN-γ stimulates intestinal macrophages to produce nitirc oxide paralyzing myocytes leading to gastrointestinal hypomotility.

SUMMARY

The involvement of the adaptive (T-helper type 1 cell-mediated immune response) and of the innate (mast cells, intestinal macrophages) immune system in the pathophysiology of POI displays possible targets for objective monitoring and treatment of POI.

Gum chewing reduces postoperative ileus? A systematic review and meta-analysis

BACKGROUND

An important cause of delayed recovery from intestinal surgery is postoperative ileus. Gum chewing is a form of sham feeding, which could encourage gastrointestinal motility through cephalic-vagal stimulation.

METHODS

We sought to identify all randomized controlled trials comparing gum chewing with standard care after elective intestinal surgery. We searched electronic databases (Cochrane, Embase, and PubMed), reference lists and contacted authors to obtain further data. We assessed the identified trials for quality and performed a meta-analysis and systematic review. The main outcome measures examined were time to flatus and stool postoperatively and length of hospital stay, which were analysed using random effect models. We also examined clinical complication rates.

RESULTS

We identified nine eligible trials that had enrolled a total of 437 patients. The intervention was well tolerated and complication rates were low. There was statistical evidence of heterogeneity for the three main outcomes. Pooled estimates showed a reduction in time to flatus by 14 h (95% CI: -20 to -8h, p=0.001), time to bowel movement by 23 h (95% CI: -32 to -15 h, p<0.001) and a reduction in length of hospital stay by 1.1 days (95% CI: -1.9 to -0.2 days, p=0.016).

CONCLUSIONS

Chewing sugarless gum following elective intestinal resection is associated with improved outcomes. Insufficient data were available to demonstrate a reduced rate of clinical complications or reduced cost. An adequately powered, methodologically rigorous trial of gum chewing is required to confirm if there are any benefits and if these result in differences in clinical outcomes such as infection.

New therapies in the treatment of postoperative ileus after gastrointestinal surgery

Postoperative ileus after gastrointestinal surgery results from many factors, including the effects of surgical trauma, anesthetic agents, hyperactivity of the sympathetic nervous system, local inflammatory reactions, and the use of opioids in the postoperative period. Postoperative ileus can lead to potential complications and may prolong patients' hospitalization, thereby leading to an increase in healthcare costs. There have been recent efforts to improve the understanding of the pathogenesis of postoperative ileus and to develop new treatments to prevent or minimize its occurrence. Here, we present a review of the factors related to the development of postoperative ileus and new therapies directed at its prevention.

Prokinetic effects of a new ghrelin receptor agonist TZP-101 in a rat model of postoperative ileus

Postoperative ileus (POI) is a major cause of postoperative complications and prolonged hospitalization. Ghrelin, which is the endogenous ligand for the growth hormone secretagogue receptor, has been found to stimulate gastric motility and accelerate gastric emptying. The present study investigates whether TZP-101 (0.03-1 mg/kg i.v.), a synthetic ghrelin-receptor agonist, could improve gastrointestinal transit in rats with POI. Since the main factors for the development of POI are the surgical manipulation and the gastrointestinal effects of opioid-receptor agonists used for pain management, the effect of TZP-101 was investigated in rats subjected to surgery, to morphine treatment (3 mg/kg s.c.), or to a combination of both. The results showed that TZP-101 is equally effective against the delayed gastrointestinal transit induced by surgery, by morphine, or by the combination of both interventions. The prokinetic action of TZP-101 was more pronounced in the stomach compared to the small intestine.

Review of the pathophysiology and management of postoperative ileus

Investigations in the pathophysiology and treatment of postoperative ileus continue to evolve. Bowel rest is no longer a mandatory component of postoperative recovery. Tolerance of enteral nutrition and normalization of the abdominal examination are more accurate indications of the resolution of postoperative ileus than passage of flatus or first bowel movement. A multimodal "fast track" recovery approach incorporated into a clinical pathway provides a more rapid return of intestinal function and shortened hospital stay in patients undergoing major, uncomplicated gastrointestinal surgery.

Postoperative nausea and vomiting

Nausea and vomiting following surgery may either occur as postoperative nausea and vomiting, which is a condition that is mainly related to anesthesia, or as secondary to postoperative ileus, which denotes inhibition of gastrointestinal motility following surgery. Postoperative ileus is a multifactorial event with several contributing mechanisms. Although postoperative nausea and vomiting pathophysiology has been quite well-studied little is known about it. There are multiple targets for treatment, prevention, and its successful empirical management e.g. by 5-HT(3) receptor antagonists. This review describes different aspects of the pathophysiology of postoperative ileus and postoperative nausea and vomiting, their relevance to postoperative care, and the standardized approach to manage postoperative nausea and vomiting that was established by Apfel and coworkers. Despite the recent advances in the understanding and treatment of conditions that trigger nausea and vomiting in the postoperative period, these symptoms remain a significant problem that affects patients' recovery, comfort, and treatment cost.

Salutary Effects of Tachykinin Receptor Antagonists in a Rat Model of Postoperative Ileus

BACKGROUND

Postoperative ileus (PI) is a common surgical complication treated mainly with supportive measures. Tachykinins control gastrointestinal motility and modulate somatic and visceral pain sensation; therefore, the effect of tachykinin receptor antagonists in a rat model of PI using NK(1-3) antagonists, SR140333, SR48968, and SR142801, was investigated.

MATERIALS AND METHODS

Intestinal transit was measured as Evans blue migration after varied nociceptive stimuli: skin incision (SI), laparotomy (LAP), or laparotomy plus gut manipulation (L + M) in anesthetized rats.

RESULTS

Diethyl ether anesthesia and SI did not influence the intestinal transit of the dye in comparison to untreated animals--UN: 61.17 +/- 5.47, 62.10 +/- 8.30, and 56.70 +/- 4.10 cm, respectively. In contrast LAP and L + M have significantly reduced intestinal motility to 26.40 +/- 2.07 and 9.70 +/- 1.15 cm, respectively. SR140333 (3-30 microg/kg), SR48968 (1-30 microg/kg), and SR142801 (3-10 microg/kg) reversed the additional inhibitory effects of gut manipulation subsequent to LAP dose-dependently, the dye transit returning with the use of the most effective antagonist doses up to 25.28 +/- 1.08, 21.70 +/- 0.19, and 25.0 +/- 1.34 cm. The combinations of submaximal doses of NK(1) and NK(3), NK(2) and NK(3) and NK(1), and NK(2) and NK(3) antagonists were not more effective than a single-agent regimen. On the other hand SR140333 and SR48968 (NK(1) + NK(2) antagonists) acted additively, the intestinal transit reaching 26.60 +/- 0.85 cm. SR140333, SR48968, and SR142801 have not affected the intestinal passage in UN rats or those undergoing SI or LAP.

CONCLUSIONS

SR140333, SR48968, and SR142801 exert a salutary action on suppressed gut motility following surgical manipulation of the gut, the combination of NK(1) and NK(2) antagonists being most beneficial.

Effects of psychological stress on small intestinal motility and expression of cholecystokinin and vasoactive intestinal polypeptide in plasma and small intestine in mice

AIM: To investigate the effects of psychological stress on small intestinal motility and expression of cholecystokinin (CCK) and vasoactive intestinal polypeptide (VIP) in plasma and small intestine, and to explore the relationship between small intestinal motor disorders and gastrointestinal hormones under psychological stress.

METHODS: Thirty-six mice were randomly divided into psychological stress group and control group. A mouse model with psychological stress was established by housing the mice with a hungry cat in separate layers of a two-layer cage. A semi-solid colored marker (carbon-ink) was used for monitoring small intestinal transit. CCK and VIP levels in plasma and small intestine in mice were measured by radioimmunoassay (RIA).

RESULTS: Small intestinal transit was inhibited (52.18±19.15% vs 70.19±17.79%, P<0.01) in mice after psychological stress, compared to the controls. Small intestinal CCK levels in psychological stress mice were significantly lower than those in the control group (0.75±0.53 μg/g vs 1.98±1.17 μg/g, P<0.01), whereas plasma CCK concentrations were not different between the groups. VIP levels in small intestine were significantly higher in psychological stress mice than those in the control group (8.45±1.09 μg/g vs 7.03±2.36 μg/g, P<0.01), while there was no significant difference in plasma VIP levels between the two groups.

CONCLUSION: Psychological stress inhibits the small intestinal transit, probably by down-regulating CCK and up-regulating VIP expression in small intestine.

Postoperative colonic motility increases after early food intake in patients undergoing colorectal surgery

BACKGROUND

Stimulation of colonic motility by the gastrocolonic response may help to reduce inhibition of gastrointestinal motility after colorectal surgery. We aimed to investigate whether postoperative colonic motility is increased after early food intake.

METHODS

Nineteen patients undergoing colorectal surgery and 7 healthy volunteers were investigated. Colonic motility was recorded with a combined manometry/barostat system, and the effect of a standard 500-kcal meal was evaluated once in healthy volunteers and in 15 patients on the first and second postoperative day. Four patients remained unfed, serving as controls.

RESULTS

In patients, the colonic motility index increased from 12 +/- 5 at baseline to 65 +/- 24 mm Hg after the meal on postoperative day 1 (mean +/- SEM; P < .01), while barostat bag volumes decreased, indicating a rise in colonic tone. On day 2, the motility index was 62 +/- 17 mm Hg at baseline and did not change after the meal. In unfed controls, no change was observed during colonic motility recordings on both postoperative days. In healthy volunteers, the colonic motility index increased from 98 +/- 52 at baseline to 151 +/- 58 mm Hg postprandially (P < .05).

CONCLUSIONS

As in healthy volunteers, there is a potential to stimulate colonic motility by early food intake in postoperative patients. This may help to improve prolonged colonic motility disorders after colorectal surgery.

Postoperative ileus: a review

PURPOSE

Postoperatively, some patients experience a prolonged inhibition of coordinated bowel activity, which causes accumulation of secretions and gas, resulting in nausea, vomiting, abdominal distension, and pain. This prolonged inhibition can take days or weeks to resolve and often is referred to as postoperative paralytic ileus lasting more than three days after surgery. This article reviews the etiology, pathophysiology, and treatment options of postoperative ileus.

METHODS

The relevant literature from 1965 to 2003 was identified and reviewed using MEDLINE database of the U.S. Medical Library of Medicine. Both retrospective and prospective studies were included in this review.

RESULTS

The pathophysiology of postoperative ileus is multifactorial. The duration of postoperative ileus correlates with the degree of surgical trauma and is most extensive after colonic surgery. However, postoperative ileus can develop after all types of surgery including extraperitoneal surgery. A variety of treatment options have been used to decrease the duration of postoperative ileus. However, it is difficult to compare these studies because of small sample sizes and differences in operations performed, anesthesia protocols provided both intraoperatively and postoperatively, patient comorbidities, and in the measured end points, such as the time to the presence of bowel sounds, flatus, or bowel movements, tolerance of solid food, or discharge from the hospital. However, despite these drawbacks, some conclusions can be made.

CONCLUSIONS

Paralytic postoperative ileus continues to be a significant problem after abdominal and other types of surgery. The etiology is multifactorial and is best treated with a combination of different approaches. Currently, the important factors that could effect the duration and recovery from postoperative ileus include limitation of narcotic use by substituting alternative medications such as nonsteroidals and placing a thoracic epidural with local anesthetic when possible. The selective use of nasogastric decompression and correction of electrolyte imbalances also are important factors to consider.

Levels of vasoactive intestinal peptide, cholecystokinin and calcitonin gene-related peptide in plasma and jejunum of rats following traumatic brain injury and underlying significance in gastrointestinal dysfunction

AIM: To study the alterations of brain-gut peptides following traumatic brain injury (TBI) and to explore the underlying significance of these peptides in the complicated gastrointestinal dysfunction.

METHODS: Rat models of focal traumatic brain injury were established by impact insult method, and divided into 6 groups (6 rats each group) including control group with sham operation and TBI groups at postinjury 3, 12, 24, 72 h, and d 7. Blood and proximal jejunum samples were taken at time point of each group and gross observations of gastrointestinal pathology were recorded simultaneously. The levels of vasoactive intestinal peptide (VIP) in plasma, calcitonin gene-related peptide (CGRP) and cholecystokinin (CCK) in both plasma and jejunum were measured by enzyme immunoassay (EIA). Radioimmunoassay (RIA) was used to determine the levels of VIP in jejunum.

RESULTS: Gastric distension, delayed gastric emptying and intestinal dilatation with a large amount of yellowish effusion and thin edematous wall were found in TBI rats through 12 h and 72 h, which peaked at postinjury 72 h. As compared with that of control group (247.8 ± 29.5 ng/L), plasma VIP levels were significantly decreased at postinjury 3, 12 and 24 h (106.7 ± 34.1 ng/L, 148.7 ± 22.8 ng/L, 132.8 ± 21.6 ng/L, respectively), but significantly increased at 72 h (405.0 ± 29.8 ng/L) and markedly declined on d 7 (130.7 ± 19.3 ng/L). However, Plasma levels CCK and CGRP were significantly increased through 3 h and 7 d following TBI (126-691% increases), with the peak at 72 h. Compared with control (VIP, 13.6 ± 1.4 ng /g; CGRP, 70.6 ± 17.7 ng/g); VIP and CGRP levels in jejunum were significantly increased at 3 h after TBI (VIP, 35.4 ± 5.0 ng/g; CGRP, 103.8 ± 22.1 ng/g), and declined gradually at 12 h and 24 h (VIP, 16.5 ± 1.8 ng/g, 5.5 ± 1.4 ng/g; CGRP, 34.9 ± 9.7 ng/g, 18.5 ± 7.7 ng/g), but were significantly increased again at 72 h (VIP, 48.7 ± 9.5 ng/g; CGRP, 142.1 ± 24.3 ng/g), then declined in various degrees on d 7 (VIP, 3.8 ± 1.1 ng/g; CGRP, 102.5 ± 18.1 ng/g). The CCK levels in jejunum were found to change in a similar trend as that in plasma with the concentrations of CCK significantly increased following TBI (99-517% increases) and peaked at 72 h.

CONCLUSION: Traumatic brain injury can lead to significant changes of brain-gut peptides in both plasma and small intestine, which may be involved in the pathogenesis of complicated gastrointestinal dysfunction.

Postoperative ileus: progress towards effective management

The pathogenesis of postoperative ileus (PI) is multifactorial, and includes activation of inhibitory reflexes, inflammatory mediators and opioids (endogenous and exogenous). Accordingly, various strategies have been employed to prevent PI. As single-modality treatment, continuous postoperative epidural analgesia including local anaesthetics has been most effective in the prevention of PI. Choice of anaesthetic technique has no major impact on PI. Minimally invasive surgery reduces PI, in accordance with the sustained reduction in the inflammatory responses, while the effects of early institution of oral nutrition on PI per se are minor. Several pharmacological agents have been employed to resolve PI (propranolol, dihydroergotamine, neostigmine, erythromycin, cisapride, metoclopramide, cholecystokinin, ceruletide and vasopressin), most with either limited effect or limited applicability because of adverse effects. The development of new peripheral selective opioid antagonists is promising and has been demonstrated to shorten PI significantly. A multi-modal rehabilitation programme including continuous epidural analgesia with local anaesthetics, enforced nutrition and mobilisation may reduce PI to 1-2 days after colonic surgery.

Postoperative ileus: etiologies and interventions

This article will review the pathophysiology of postoperative ileus, with emphasis on potential therapeutic targets, and examine the efficacy of pharmacologic and nonpharmacologic interventions. Proposed mechanisms include actuation of spinal and local sympathetic neural reflexes, inflammatory mediation, and exacerbation by anesthetic or surgical procedures. Some procedures or agents have shown clinical benefit, and these include use of laparoscopic surgery, thoracic epidurals, nonsteroidal anti-inflammatory drugs, and opiate antagonists. Other procedures may be helpful with low risk of adverse effects. These include early feeding and ambulation, laxatives, and possibly neostigmine.

Prostanoid production via COX-2 as a causative mechanism of rodent postoperative ileus

BACKGROUND & AIMS

This study demonstrates a significant role for cyclooxygenase (COX)-2 and prostanoid production as mechanisms for surgically induced postoperative ileus.

METHODS

Rats, COX-2+/+, and COX-2-/- mice underwent simple intestinal manipulation. Reverse-transcription polymerase chain reaction and immunohistochemistry were used to detect and localize COX-2 expression. Prostaglandin levels were measured from serum, peritoneal lavage fluid, and muscularis culture media. Jejunal circular muscle contractions were measured in an organ bath, and gastrointestinal transit was measured in vivo.

RESULTS

The data show that intestinal manipulation induces COX-2 messenger RNA and protein within resident muscularis macrophages, a discrete subpopulation of myenteric neurons and recruited monocytes. The manipulation-induced increase in COX-2 expression resulted in significantly elevated prostaglandin levels within the circulation and peritoneal cavity. The source of these prostanoids could be directly attributed to their release from the inflamed muscularis externa. As a consequence of the molecular up-regulation of COX-2, we observed a decrease in in vitro jejunal circular muscle contractility and gastrointestinal transit, both of which could be alleviated pharmacologically with selective COX-2 inhibition. These studies were corroborated with the use of COX-2-/- mice.

CONCLUSIONS

Prostaglandins, through the induction of COX-2, are major participants in rodent postoperative ileus induced by intestinal manipulation.

Postoperative ileus: a preventable event

BACKGROUND

Postoperative ileus has traditionally been accepted as a normal response to tissue injury. No data support any beneficial effect of ileus and indeed it may contribute to delayed recovery and prolonged hospital stay. Efforts should, therefore, be made to reduce such ileus.

METHODS

Material was identified from a Medline search of the literature, previous review articles and references cited in original papers. This paper updates knowledge on the pathophysiology and treatment of postoperative ileus.

RESULTS AND CONCLUSION

Pathogenesis mainly involves inhibitory neural reflexes and inflammatory mediators released from the site of injury. The most effective method of reducing ileus is thoracic epidural blockade with local anaesthetic. Opioid-sparing analgesic techniques and non-steroidal anti-inflammatory agents also reduce ileus, as does laparoscopic surgery. Of the prokinetic agents only cisapride is proven beneficial; the effect of early enteral feeding remains unclear. However, postoperative ileus may be greatly reduced when all of the above are combined in a multimodal rehabilitation strategy.

Evidence for VIP(1)/PACAP receptors in the afferent pathway mediating surgery-induced fundic relaxation in the rat

We previously reported activation of an inhibitory adrenergic and a non-adrenergic non-cholinergic (NANC) pathway during abdominal surgery relaxing the rat gastric fundus. In the present study, we investigated the possible role of nitric oxide (NO) and vasoactive intestinal polypeptide (VIP) in the NANC part of the surgery-induced fundic relaxation. The effect of the NO biosynthesis inhibitor N(G)-nitro-L-arginine (L-NOARG), the non-selective VIP receptor antagonist [D-p-Cl-Phe(6),Leu(17)]-VIP and the selective VIP(1) receptor antagonist [Acetyl-His(1),D-Phe(2),Lys(15),Arg(16), Leu(17)]-VIP was investigated on the non-adrenergic fundic relaxation induced by manipulation of the small intestine followed by resection of the caecum. Guanethidine partly reduced the manipulation-induced fundic relaxation. Addition of L-NOARG reduced this non-adrenergic component, whereas the non-selective VIP receptor antagonist had no significant effect. Combination of L-NOARG and the non-selective VIP antagonist however further reduced the relaxation to manipulation. The selective VIP(1) receptor antagonist reduced the mean and maximal relaxation induced by abdominal surgery in the presence of guanethidine. When combined with L-NOARG, the relaxation of the gastric fundus was almost completely abolished. The VIP(1) receptor antagonist alone had no significant effect on the mean and maximal relaxation, but enhanced recovery of fundic tone. In conclusion, as VIP(1) receptors are not present in the rat gastric fundus, these results suggest that the NANC inhibitory pathway activated during abdominal surgery involves VIP(1) receptors, most likely in the afferent limb. The inhibitory neurotransmitters released at the level of the gastric fundus smooth muscle are NO and a substance different from VIP.

Postoperative colonic motility and tone in patients after colorectal surgery

PURPOSE

Colonic motility is crucial for the resolution of postoperative ileus. However, few data are available on postoperative colonic motility and no data on postoperative colonic tone. We aimed to characterize postoperative colonic tone and motility in patients.

METHODS

Nineteen patients were investigated with combined barostat and manometry recordings after left colonic surgery. During surgery a combined recording catheter was placed in the colon with two barostat bags and four manometry channels cephalad to the anastomosis. Recordings were performed twice daily from Day 1 to Day 3 after surgery.

RESULTS

Manometry showed an increasing colonic motility index, which was a mean (+/- standard error of the mean) of 37 +/- 5 mmHg/minute on Day 1, 87 +/- 19 mmHg/minute on Day 2, and 102 +/- 13 mmHg/minute on Day 3 (P < 0.05 for Day 1 vs. Day 2 and Day 2 vs. Day 3). Low barostat bag volumes indicating a high colonic tone were observed on Day 1 after surgery and increased subsequently (barostat bag I was 19 +/- 4, 32 +/- 6, and 32 +/- 6 ml; barostat bag II was 13 +/- 1, 19 +/- 3, and 22 +/- 5 ml on Days 1, 2, and 3, respectively; for both barostat bags P < 0.05 for Day 1 vs. Day 2 but not Day 2 vs. Day 3).

CONCLUSIONS

Colonic motility increased during the postoperative course. The low barostat bag volumes indicated a high colonic tone postoperatively which would correspond to a contracted rather than to a distended colon. High colonic tone postoperatively may be relevant for pharmacologic treatment of postoperative ileus.

Products of cyclooxygenase-2 catalysis regulate postoperative bowel motility

Laparotomy involving manipulation of the small intestine causes injury, initiating an inflammatory cascade in the small bowel wall, which generates eicosanoids and proinflammatory cytokines. We have shown that ketorolac and salsalate, nonselective cyclooxygenase (COX) inhibitors, ameliorate postoperative small bowel ileus in a rodent model. Others have shown that interleukin-1 receptor antagonism improves postoperative gastric emptying. We examined whether inhibition of the proinflammatory cytokines, tumor necrosis factor alpha (TNFalpha) and interleukin-1 (IL-1), or selective blockade of cyclooxygenase-2 (COX-2), the COX isoform induced during inflammation, would accelerate postoperative small bowel transit in our model. Duodenostomy tubes were inserted into male Sprague-Dawley rats. One week later, animals were randomized to receive TNF-binding protein (TNF-bp), IL-1 receptor antagonist (IL-1ra), or saline (NS) prior to standardized laparotomy. Additional rats were gavaged preoperatively with a selective COX-2 inhibitor (NS-398) or NS. Small intestinal transit was measured as the geometric center (GC) of distribution of (51)CrO(4) at 30 min, 3 h, or 6 h (n = 5-9 rats/group) following laparotomy. Selective inhibition of COX-2 significantly increased postoperative small bowel transit compared to controls (GC 2.9 +/- 0.3 vs 2.2 +/- 0.1 at 30 min, GC 2.9 +/- 0.3 vs 2.5 +/- 0.2 at 3 h, and GC 3.3 +/- 0.3 vs 2.8 +/- 0.2 at 6 h, P < 0.05). In contrast, neither TNF-bp nor IL-1ra altered postoperative small intestinal transit in this model. Use of selective COX-2 inhibitors may accelerate recovery of postoperative bowel dysmotility without the undesirable effects (e.g., gastrointestinal irritation and anti-platelet effect) of nonselective COX inhibitors.

Role of VIP1/PACAP receptors in postoperative ileus in rats

1. Vasoactive intestinal polypeptide (VIP) is an inhibitory neurotransmitter in the enteric nervous system. We investigated the role of VIP1/PACAP receptors in postoperative ileus in rats. 2. Different degrees of inhibition of the gastrointestinal transit, measured by the migration of Evans blue, were achieved by skin incision, laparotomy or laparotomy plus mechanical stimulation of the gut. 3. The transit after skin incision or laparotomy was not altered by the VIP1/PACAP receptor antagonist Ac-His1,D-Phe2, K15, R16, VIP(3-7), GRF(8-27)-NH2 nor by the VIP1/PACAP receptor agonist K15, R16, VIP(1-7), GRF(8-27)-NH2 and the VIP2/PACAP receptor agonist RO 25-1553 (5 microg kg(-1)). 4. However, the transit after laparotomy plus mechanical stimulation was significantly enhanced by the VIP1/PACAP receptor antagonist, whereas it was further inhibited by the VIP1/PACAP receptor agonist. The combination of the VIP1/PACAP receptor agonist and antagonist counteracted the effect of both drugs alone. The VIP2/PACAP receptor agonist did not alter the effect of the VIP1/PACAP receptor antagonist. 5. The combination of the VIP1/PACAP receptor antagonist plus the nitric oxide (NO) synthase inhibitor L-nitroarginine had no effect on the transit after laparotomy plus mechanical stimulation, while the transit after skin incision was significantly decreased. 6. These findings suggest the involvement of VIP1/PACAP receptors, next to NO, in the pathogenesis of postoperative ileus. However, the combination of the VIP1/PACAP antagonist and the NO synthase inhibitor abolished the beneficial effect of each drug alone, suggesting the need for one of the inhibitory neurotransmitters to enable normal gastrointestinal transit.

Implications of tachykinins and calcitonin gene-related peptide in inflammatory bowel disease

Calcitonin gene-related peptide (CGRP) and the preprotachykinin A gene-derived peptides substance P (SP) and neurokinin A (NKA) are expressed in extrinsic primary afferent nerve fibres and intrinsic enteric neurons of the gut. The actions of tachykinins on the digestive effector systems are mediated by three different types of tachykinin receptor, termed NK1, NK2 and NK3 receptors, while the gastro-intestinal actions of CGRP are brought about by CGRP1 and possibly other CGRP receptors. These neuropeptide transmitters are expressed by enteric neurons, intestinal muscle, epithelium and vascular system in a cell-specific manner and enable SP, NKA and CGRP to influence motility, electrolyte and fluid secretion, vascular and immune functions in a peptide- and region-specific fashion. Inflammatory disorders of various aetiology involve changes in the peptidergic innervation of the gut, and inflammatory bowel disease is associated with NK1 receptor upregulation in intestinal blood vessels and lymphoid structures. Some of these alterations are reproduced in experimental models of gastro-intestinal disease, and there is mounting evidence that an imbalanced function of peptidergic neurons contributes to motor, secretory, vascular and immunological disturbances in intestinal anaphylaxis, infection and inflammation. In a therapeutic perspective it seems conceivable that tachykinin and CGRP receptors antagonists can be employed as spasmolytic, antidiarrhoeal, anti-inflammatory and antinociceptive drugs.

Calcitonin gene-related peptide and spinal afferents partly mediate postoperative colonic ileus in the rat

BACKGROUND

Calcitonin gene-related peptide (CGRP) is a widely distributed neuropeptide contained in intrinsic and extrinsic neurons of the gastrointestinal wall that has been shown to be released by noxious stimulation, to be involved in nociception, to inhibit gastrointestinal motility, and to partly mediate postoperative gastric ileus. We hypothesized that abdominal surgery-induced release of CGRP might inhibit postoperative colonic motility and food intake.

METHODS

Colonic transit, stool pellet number, stool pellet weight, and food intake were measured for 48 hours after induction of postoperative ileus in rats. CGRP was immunoneutralized by preoperative injection of CGRP monoclonal antibody, or visceral afferent nerve fibers containing CGRP were functionally ablated by topical capsaicin treatment of the vagus nerves or of the celiac/superior mesenteric ganglia before abdominal surgery.

RESULTS

Abdominal surgery increased colonic transit time and decreased 24-hour cumulative stool pellet number, stool pellet weight, and food intake. CGRP immunoneutralization reversed postoperative inhibition of colonic transit, 24-hour cumulative stool pellet number, stool pellet weight, and food intake by 77%, 82%, 80%, and 52%, respectively. Whereas ablation of vagal afferent nerve fibers had no effect, spinal afferent nerve fiber ablation reversed postoperative inhibition of 24-hour cumulative stool pellet number, stool pellet weight, and food intake by 41%, 38%, and 19%, respectively.

CONCLUSIONS

CGRP and spinal afferent nerve fibers partly mediate postoperative colonic ileus and inhibition of food intake in the rat. By the magnitude of reversal of postoperative ileus, CGRP seems to be an important mediator of postoperative colonic ileus. Our results for the first time show involvement of a neuropeptide and spinal afferents in the mediation of postoperative colonic ileus and postoperative inhibition of food intake in rats.

Neural emergency system in the stomach

The maintenance of gastric mucosal integrity depends on the rapid alarm of protective mechanisms in the face of pending injury. Afferent neurons of extrinsic origin constitute an emergency system that is called into operation when the gastric mucosa is endangered by acid and other noxious chemicals. The function of these chemoceptive afferents can be manipulated selectively and explored with the excitotoxin capsaicin. Most of the homeostatic actions of capsaicin-sensitive afferents are brought about by peptides released from their peripheral endings in the gastric wall. When stimulated, chemoceptive afferents enhance gastric blood flow and activate hyperemia-dependent and hyperemia-independent mechanisms of protection and repair. In the rodent stomach, these local regulatory roles of sensory neurons are mediated by calcitonin gene-related peptide acting via calcitonin gene-related peptide 1 receptors and neurokinin A acting via neurokinin 2 receptors, with both peptides using nitric oxide as their common messenger. In addition, capsaicin-sensitive neurons form the afferent arc of autonomic reflexes that control secretory and motor functions of the stomach. The pathophysiological potential of the neural emergency system is best portrayed by the gastric hyperemic response to acid backdiffusion, which is signaled by afferent nerve fibers. This mechanism limits damage to the surface of the mucosa and creates favorable conditions for rapid restitution and healing of the wounded mucosa.

A model to investigate postoperative ileus with strain gauge transducers in awake rats

BACKGROUND

Postoperative ileus influences patients well-being, hospital stay, and health cost, and postoperative inhibition of colonic motility is a major contributor to postoperative ileus. Experimental models for investigating postoperative ileus are needed. In particular, recording of postoperative colonic motility in awake rats has not been described yet.

MATERIAL AND METHODS

Gastric, small intestinal, and colonic motility were recorded with strain gauge transducers in awake rats, and the effects of anesthesia and abdominal surgery on gastrointestinal motility were investigated.

RESULTS

Ether anesthesia increased gastric motility and inhibited small intestinal motility, while enflurane anesthesia had only minor effects on gastrointestinal motility. Abdominal surgery inhibited gastric, small intestinal, and colonic motility, and a detailed analysis of gastrointestinal motility in our postoperative ileus model is given.

CONCLUSIONS

We established a model to record gastric, small intestinal, and colonic motility in awake rats postoperatively. We could demonstrate that enflurane anesthesia had little effect on gastrointestinal motility, while laparotomy and short manipulation of the cecum produced a prolonged inhibition of gastrointestinal motility. Our model could be used to investigate postoperative ileus, particularly of the colon, in awake rats.

Characterization of VIP receptor-effector system antagonists in rat and mouse peritoneal macrophages

In the present study we show that the synthetic peptides [4-Cl-D-Phe6,Leu17]VIP and the growth hormone releasing factor (GRF) analog [Ac-Tyr1,D-Phe2]GRF-(1-29)-NH2 inhibit in a competitive manner the specific [125I]VIP binding to both rat and mouse peritoneal macrophages. In rat peritoneal macrophages, the order of potency of the different peptides, as expressed by the IC50 values was: VIP (IC50 = 1.90 +/- 0.16 nM) > [4-Cl-D-Phe6,Leu17]VIP (IC50 = 125.8 +/- 13.2 nM) > [Ac-Tyr1,D-Phe2]GRF-(1-29)-NH2 (IC50 = 354.8 +/- 21.2 nM). In mouse peritoneal macrophages a similar pattern of potency was observed: VIP (IC50 = 1.58 +/- 0.12 nM) > [4-Cl-D-Phe6,Leu17]VIP (IC50 = 110.8 +/- 10.7 nM) > [Ac-Tyr1,D-Phe2]GRF-(1-29)-NH2 (IC50 = 251 +/- 19.2 nM). The behavior as VIP receptor antagonists of both [4-Cl-D-Phe6,Leu17]VIP and [Ac-Tyr1,D-Phe2]GRF-(1-29)-NH2 in rat and mouse peritoneal macrophages was confirmed by: (a) the shift to the right of VIP dose-stimulated cyclic AMP production curves in the presence of the two antagonists; (b) the agreement between the order of efficacy of the two peptides in competition experiments with the corresponding inhibition of cyclic AMP production; (c) the inefficiency of the two antagonists on the stimulation of cyclic AMP production by the beta-adrenoceptor agonist isoproterenol, which indicates the specificity of the interaction; (d) the synergic effect of VIP on isoproterenol-stimulated cyclic AMP production was completely abolished by [4-Cl-D-Phe6,Leu17]VIP or [Ac-Tyr1,D-Phe2]GRF-(1-29)-NH2, suggesting that both antagonists acted via specific VIP receptors. Moreover, propranolol, a beta-adrenoceptor antagonist, did not affect the VIP-stimulated cyclic AMP production and the antagonist role of [4-Cl-D-Phe6,Leu17]VIP or [Ac-Tyr1,D-Phe2]GRF-(1-29)-NH2; (e) in cross-linking experiments, the intensity of the labeling of the [125I]VIP/receptor complexes was significantly lower with the antagonists than in the control experimental situation in both mouse and rat peritoneal macrophage membranes.

Tachykinins in the gut. Part I. Expression, release and motor function

The preprotachykinin-A gene-derived peptides substance P and neurokinin (NK) A are expressed in distinct neural pathways of the mammalian gut. When released from intrinsic enteric or extrinsic primary afferent neurons, tachykinins have the potential to influence both nerve and muscle by way of interaction with three different types of tachykinin receptor, termed NK1, NK2 and NK3 receptors. Most prominent among the effects of tachykinins is their excitatory action on gastrointestinal motor activity, which is seen in virtually all regions and layers of the mammalian gut. This action depends not only on a direct activation of the muscle through NK1 and/or NK2 receptors, but also on stimulation of excitatory enteric motor pathways through NK3 and/or NK1 receptors. In addition, tachykinins can inhibit motor activity by stimulating either inhibitory neuronal pathways or interrupting excitatory relays. A synopsis of the available data indicates that endogenous substance P and NKA interact with other enteric transmitters in the physiological control of gastrointestinal motor activity. Derangement of the regulatory roles of tachykinins may be a factor in the gastrointestinal dysmotility associated with infection, inflammation, stress and pain. In a therapeutic perspective, it would seem conceivable, therefore, that tachykinin agonists and antagonists are adjuncts to the treatment of motor disorders that involve pathological disturbances of the gastrointestinal tachykinin system.

Salsalate, morphine, and postoperative ileus

BACKGROUND

Previously, we demonstrated that ketorolac, a nonsteroidal antiinflammatory drug (NSAID), prevented postoperative small bowel ileus in a rodent model. The aim of this study was to evaluate the effect of salsalate, an NSAID without antiplatelet effect, on postoperative ileus alone or in combination with morphine.

METHODS

Forty-eight rats underwent placement of duodenal catheters and were then randomly assigned to one of eight groups (n = 6). Four groups had standardized laparotomy following drug administration, whereas 4 groups underwent the same treatment without laparotomy: control and morphine animals received 0.1 mL alcohol via the catheter, whereas salsalate and salsalate-plus-morphine animals received salsalate (15 mg/kg) dissolved in 0.1 mL alcohol. The animals also received 0.5 mg/kg morphine (morphine and salsalate plus morphine) or the same volume of saline (control and salsalate) subcutaneously. Transit was measured following the injection of a nonabsorbed marker via the duodenal catheter and is defined as the geometric center (GC) of distribution. An additional 20 rats had serosal electrodes placed on the jejunum, and were assigned to one of four treatment groups (control, salsalate, morphine, and salsalate plus morphine; n = 5 each group). Myoelectric activity was recorded until the reappearance of the migrating myoelectric complex (MMC) following laparotomy.

RESULTS

Laparotomy and morphine independently reduced small bowel transit (P = 0.0006 and 0.006, respectively, by three-way analysis of variance [ANOVA]; GC 4.3 +/- 0.2 control versus 2.2 +/- 0.3 laparotomy versus 3.6 +/- 0.4 morphine), but morphine did not further worsen postoperative transit (GC 2.4 +/- 0.4; P = 0.42). Although salsalate did not alter baseline transit, pretreatment improved postoperative transit (P = 0.0002; GC 3.6 +/- 0.4). This effect was lost with the addition of morphine (GC 2.7 +/- 0.2; P = 0.21). The MMCs returned earlier after laparotomy in salsalate-pretreated rats (63 +/- 18 minutes salsalate versus 160 +/- 12 minutes laparotomy; P < 0.01, one-way ANOVA). However, this effect was also lost in animals receiving morphine (106 +/- 16 min; P > 0.05).

CONCLUSION

Salsalate improves postoperative small bowel motility in a rodent model; however, this effect is masked by morphine.