Effect Of Gastrointestinal Motility On Intestinal Mucosal Barrier After Acute Gastrointestinal Injury And The Intervention Study

Acute gastrointestinal injury(AGI)is malfunctioning of the gastrointestinal(GI)tract in critically ill patients due to their acute illness.Various severity of AGI may occur in the majority of patients in critical illness,which is an important factor leading to an unfavorable prognosis.However,AGI hasn’t been paid enough attention until the European Society of Intensive Care Medicine presented the opinion of AGI in 2012.As two important aspects of intestinal function,the function of intestinal motility and intestinal mucosal barrier is very important in the treatment and prognosis of patients with AGI.We supposed that injured intestinal motility may have a causal relationship with the impaired intestinal mucosal barrier after AGI,affecting each other reciprocally and forming a vicious cycle,which could worsen the GI dysfunction and lead to other complications.At present,there is no research studying on the relationship between intestinal motility and mucosal barrier.Therefore,it is helpful to improve the management of AGI through studying the effects of AGI on GI motility and intestinal mucosal barrier,and investigate the effects of changed GI motility on intestinal mucosal barrier.Prucalopride is a high-affinity,selective 5-HT4 receptor agonist,which could active on neuronic 5-HT4 receptor of intestinal nervous system and perform a powerful prokinetic intestinal function.Comparing to previous prokinetic drugs,prucalopride is highly selective for 5-HT4 receptor,which makes it less functional on non-target organs and less side-effects.Therefore,we could provide more scientific basis for the management of AGI by studying the effect of the prucalopride on the intestinal motility,and the effect of changed intestinal motility on intestinal mucosal barrier.When the patients are suffering AGI,the transportation of the contents of intestinal tract is delayed,and even reflux happens.When lower GI tract reflux occurs,contents in the distal colon would destroy the balance of microbiota in proximal small intestine.Therefore,studying the effects of performing an ileostomy,cutting off the ceco-ileal reflux,on the GI motility and intestinal mucosal barrier after intestinal I/R injury could provide new theoretical evidence for the chosen of surgical intervention when conservative treatment for AGI failed.Enteral nutrition has been considered one of the most important therapies to manage AGI.To reach a better therapeutic effect,upgrading the content of enteral nutrition is necessary.Patients with AGI always have a partially or completely enteral feeding intolerance,which could lead to a long-term negative nitrogen balance and poor prognosis.Compared to regular EN,lipid-rich EN adds more lipid to the contents.Previous studies have shown that lipid-rich EN can significantly improve the GI motility and ameliorate intestinal inflammation.Therefore,studying the effect of lipid-rich EN on GI motility and intestinal mucosal barrier after intestinal I/R injury could provide more theoretical evidence for enteral feeding of AGI.This project used a rat model of intestinal I/R injury to represent AGI.We studied the effects of intestinal I/R injury on the GI motility,GI and systemic inflammation,and intestinal mucosal barrier,and investigated the effects of improving GI motility on intestinal mucosal barrier.Through exploring associated mechanism,this project could provide reference for improving clinical protocol,improve the therapeutic effect and overall survival.Part Ⅰ:Effect of intestinal ischemia/reperfusion injury on intestinal motility and intestinal mucosalObjective:To study the relationship between injured intestinal motility and impaired intestinal mucosal barrier after AGI in rats by the investigation of the changes of intestinal motility,inflammatory response and intestinal mucosal barrier in rats after intestinal ischemia-reperfusion for different time.Methods:Forty-eight Sprague-Dawley rats were randomized into six groups(8/group).For one sham group,superior mesenteric artery(SMA)was isolated after the laparotomy;for other five groups,rats were divided into the groups with reperfusion for 2,4,6,12 and 24 h after the ischemia of SMA for 60 min.Blood and terminal ileum were sampled from the rats which were sacrificed in every group.Intestinal motility was determined by measuring intestinal distribution of nonabsorbable FITC-dextran,serum TNF-α,IL-1β,IL-6 and IL-10 levels were determined by ELISA,serum DAO,D-lactate and I-FABP levels were determined by ELISA,mRNA levels of intestinal TNF-α,IL-1β,IL-6 and IL-10 were determined by rt-PCR.Results:Compared with the sham group,intestinal FITC-dextran MGC decreased significantly(P<0.05)in rats with intestinal I/R injury,which showed intestinal motility decreased significantly to the lowest in 4 h and tented to return in 6 h with the length of reperfusion.Compared with sham group,serum,intestinal TNF-α,IL-1β,IL-6 and IL-10 levels reached a peak in 4-6 h after intestinal I/R injury(P<0.05);intestinal TNF-α,IL-1β and IL-10 level of mRNA reached a peak in 2-6 h(P<0.05),which showed the changes of impaired intestinal mucosal barrier.Geometric Center(GC)and serum DAO,D-lactate and I-FABP had an opposite tendency.(r2 are 0.7004,0.5039 and 0.5948).Conclusion:Intestinal I/R injury could induce damage to the injured intestinal motility and the impaired intestinal mucosal barrier,which reached a peak in 4 h with the length of reperfusion,the level of intestinal motility had a positive correlation with the level of intestinal mucosal barrier.Part Ⅱ:Effect of changing intestinal motility on intestinal mucosal barrier in a rat model of intestinal ischemia/reperfusion injuryStudy I:Effect of Prucalopride on intestinal motility and intestinal mucosal barrier in a rat model of intestinal ischemia/reperfusion injuryObjective:To study the effect of changing intestinal motility on intestinal mucosal barrier after intestinal I/R injury in rat by the investigation of the effect of Prucalopride on intestinal motility,inflammatory response and intestinal mucosal barrier in rats after intestinal I/R injury.Methods:Thirty-two SD rats were randomized into four groups(8/group).For one sham group,only SMA was isolated after the laparotomy;for other three experimental group,the rats were given saline(I/R),Prucalopride 1 mg/kg weight(I/R+P1)and Prucalopride 5 mg/kg body weight(BW)(I/R+P5)via gavaga at the beginning of reperfusion after the ischemia of SMA for 60 min and the reperfusion of SMA for 4 h.Blood and terminal ileum were sampled from the rats which were sacrificed in every group.Intestinal motility was determined by measuring intestinal distribution of nonabsorbable FITC-dextran,serum TNF-α,IL-1β,IL-6 and IL-10 levels were determined by ELISA,serum DAO,D-lactate and I-FABP levels were determined by ELISA,mRNA levels of intestinal TNF-α,IL-1β,IL-6 and IL-10 were determined by rt-PCR.Results:Compared with the sham group,intestinal I/R injury could induce damage to the intestinal motility and the intestinal mucosal barrier.Compared with the I/R group,MGC increased significantly(P<0.05)and intestinal motility improved significantly by giving Prucalopride 5 mg/kg;serum and intestinal tract TNF-α,IL-1β,IL-6 and IL-10 level decreased significantly(P<0.05);intestinal TNF-α,IL-1β and IL-10 level of mRNA decreased significantly,which ameliorated intestinal and systemic inflammatory response;levels of serum DAO,D-lactate and I-FABP decreased significantly(P<0.05),which showed intestinal mucosal barrier injury improved significantly.Compared with I/R group,the Prucalopride 1 mg/kg group wasn’t considered to indicate statistical significance.In conclusion:Prucalopride 5 mg/kg could significantly improve gastrointestinal dysfunction after I/R injury and could to some extent ameliorate impaired intestinal mucosal barrier.Study Ⅱ:Effect of ileostomy on intestinal motility and intestinal mucosal barrier in a rat model of intestinal ischemia/reperfusion injuryObjective:To explore associated mechanism by the investigation of effect of ileostomy on intestinal motility,systemic inflammatory response,bacterial translocation and intestinal mucosal barrier in rats after intestinal I/R injury.Methods:Thirty-two SD rats were randomized into four groups(8/group).For one sham group,only SMA was isolated after the laparotomy;for two groups of other three experimental groups,the rats were received I/R+Ra and I/R+ileostomy at the beginning of reperfusion after the ischemia of SMA for 60 min and the reperfusion of SMA for 4 h.Blood,liver,spleen,kidneys,lymph nodes,feces in ileum and terminal ileum were sampled from the rats which were sacrificed in every group.Intestinal motility was determined by measuring intestinal distribution of nonabsorbable FITC-dextran,serum endotoxin,serum TNF-α,IL-6 and IL-10 levels were determined by ELISA,MPO activity in ileum was determined by colorimetric method;bacterial translocation in liver,spleen,kidneys,lymph nodes and blood and the number of bacterial in feces of ileum were observed by bacteria culture;the ileum was received H&E pathologic examination,the ultra-microstructure was examined by transmission electron microscope and the intestinal tight junction proteins were measured by immunofluorescence.The contents of intestinal tight junction proteins ZO-1 and claudin-1 were measured by Western Blot(WB)by scraping intestinal mucosa.Results:Compared with the sham group,intestinal I/R injury induced damage to both of the intestinal motility and the intestinal mucosal barrier.Compared with I.R+RA,MGC increased significantly and the intestinal motility improved significantly in the I/R+ileostomy group(P<0.05);positive rate of bacteria culture in the liver and lymph nodes and the number of bacteria in ileum decreased significantly;serum endotoxin,TNF-α,and IL-6 levels decreased significantly(P<0.05);WB and the immunofluorescence showed the contents of tight junction proteins claudin-1 increased significantly;the transmission electron microscope showed tight junction density recovered,desmosomes increased and structure was complete;the MPO activity in ileum decreased significantly.Conclusions:ileostomy protected the injured intestinal motility and impaired intestinal mucosal barrier after intestinal I/R injury,which was related to the remission of small intestinal bacterial overgrowth.Part III:Effect of lipid-rich enteral nutrition on intestinal motility and intestinal mucosal barrier in the model of intestinal ischemia/reperfusion injury.Objective:To explore the relationship between intestinal motility and intestinal mucosal barrier after intestinal I/R injury by the investigation of the changes of intestinal motility,inflammatory response and intestinal mucosal barrier in rats after the intestinal ischemia-reperfusion for different time.Methods:Thirty-two SD rats were randomized into four groups(8/group).For one sham group,only SMA was isolated after the laparotomy;for other three experimental groups,the rats were given the same saline(I/R),I/R+CN and I/R+LR via gavage at the beginning and in the end of the surgery after the ischemia of SMA for 60 min and the reperfusion of SMA for 4 h.Blood and terminal ileum were sampled from the rats which were sacrificed in every group.Intestinal motility was determined by measuring intestinal distribution of nonabsorbable FITC-dextran,serum,intestinal tract TNF-α,IL-6 and IL-10 levels were determined by ELISA,serum D-lactate and I-FABP levels were determined by ELISA;The contents of intestinal tight junction proteins ZO-1 and claudin-1 were measured by Western Blot(WB)by scraping intestinal mucosa.Results:Compared with the sham group,intestinal I/R injury induced damage to both of the intestinal motility and the intestinal mucosal barrier.Compared with IR+CN,MGC increased significantly and the intestinal motility improved significantly in the I/R+LR group(P<0.05);ileum TNF-αand IL-10 levels decreased significantly(P<0.05);serum TNF-alevel decreased significantly(P<0.05),which showed intestinal and systemic inflammatory response were ameliorated;serum I-FABP level decreased significantly(P<0.05),which showed impaired intestinal mucosal barrier was improved;intestinal tight junction proteins ZO-1 and claudin-1 increased significantly.Conclusion:Lipid-rich enteral nutrition could significantly improve gastrointestinal motility after I/R injury,significantly ameliorate intestinal inflammatory response and improve impaired intestinal mucosal barrier.