| Peritoneal air exposure is a common clinical phenomenon,especially during the open abdominal operation.It is well known that peritoneal air exposure may lead to stress response and further induce injury to various tissues/organs.However,it is unclear what injury it may induce,and there are little related studies.This problem has long been ignored.It is demonstrated that the cause of the faster recovery of gastrointestinal function after laparoscopic surgery versus open abdominal surgery is related to the factors,such as less tissue injury,less inflammatory reaction,less bleeding,and other factors.However,it is not sufficient to make clear this advantage just through these factors'consideration.It is well known that peritoneal air exposure is the major difference between laparoscopic surgery and open abdominal surgery.In clinical practice,gut will suffer from edema and expansion rapidly when it is exposed to air during the open abdominal surgery.In open abdomen,gut will also have a penetrating injury,and even have a intestinal air fistula,when it is exposed to air for a long time.Therefore,gut may be the major injuryed organ during peritoneal air exposure,and this may be one of the major cause of the faster recovery of gastrointestinal function.However,it is unclear whether peritoneal air exposure may induce injury to gut,and the related study is also very little.The intestinal tract is the central target organ during various stress,which is considered as a motor of multiple organ dysfunction syndrome(MODS).For fast track recovery and good outcome after surgery,it is important to prevent and avoid intestinal injury caused by different factors,especially to protect the intestinal mucosal barrier and intestinal motility,and this topic has gained increasing attention.However,it is not clear whether there are any changes in intestinal mucosal barrier and intestinal motility after peritoneal air exposure,and it also lacks related research.There has been a great progress in nutrition support during the last quarter century of 20th century.Nutrition support is one of important treatments in perioperative period.Enteral nutrition has been considered as a preferred way of nutritional support because of its advantages including coincidence with physiology and fewer complications.The therapeutic effect of enteral nutrition can be significantly enhanced when immune substance(fish oil,glutamine,etc.)is added to the enteral nutrition or the proportion of enteral nutrition component is optimized.Lipid enriched enteral nutrition is made from standard enteral nutrition plus additional fat.It is demonstrated that lipid enriched enteral nutrition could protect intestinal mucosal barrier in rats with hemorrhagic shock,reduce systemic inflammation and the degree of bacterial translocation,and also reduce intestinal inflammation and further promote gastrointestinal motility in rats after intestinal surgery.Therefore,the object of this project is to study the effect of peritoneal air exposure on intestinal injury by investigating the effect of peritoneal air exposure on intestinal mucosal barrier and intestinal motility,and to study the protective effect of lipid enriched enteral nutrition on intestinal injury through the application of lipid enriched enteral nutrition in rats with peritoneal air exposure.Part ?Effect of peritoneal air exposure on intestinal mucosal barrier Study I Dynamic intestinal mucosa stracture changes after peritoneal air exposureObjective:To assess dynamic intestinal mucosa stracture changes after peritoneal air exposure for different time.Methods:Thirty Sprague-Dawley rats were randomized into five groups(6/group):a control group,a sham group,and three exposure groups with peritoneal air exposure for 1,2,and 3h,respectively.For the exposure groups,rats received a 3cm midline abdominal incision,and then the wound edge was retracted to allow for maximal peritoneal air exposure for 1,2,and 3h,respectively.Thereafter,the abdomen was closed in one layer with 3-0 silk continuous suture.For the sham group,the animals underwent the same anesthesia and operation procedure but without laparotomy.For the control group,the animals underwent the same anesthesia but without any operative procedures.At 24h after surgery,terminal ileum were sampled to examin the histopathology and the ultra microstructure using light microscope and transmission electron microscope respectively.Results:The results in the histopathology and the ultra microstructure revealed that the intestinal mucosal morphology and ultra microstructure both had different levels of injury after peritoneal air exposure,which were proportional to the time length of peritoneal air exposure.Compared with the group with peritoneal air exposure for 1h,the group with peritoneal air exposure for 3h showed a significantly increased Chiu's scores(p<0.05),indices for intestinal mucosal injury.Conclusion:Peritoneal air exposure could induce intestinal mucosal stracture injury,which was proportional to the time length of peritoneal air exposure.Study ? Effect of peritoneal air exposure on intestinal mucosal barrierObjective:To study the effect of peritoneal air exposure on intestinal mucosal barrier.Methods:Thirty Sprague-Dawley rats were randomized into five groups(6/group):a control group,a sham group,and three exposure groups with peritoneal air exposure for 1,2,and 3h,respectively.For the exposure groups,rats received a 3cm midline abdominal incision,and then the wound edge was retracted to allow for maximal peritoneal air exposure for 1,2,and 3h,respectively.Thereafter,the abdomen was closed in one layer with 3-0 silk continuous suture.For the sham group,the animals underwent the same anesthesia and operation procedure but without laparotomy.For the control group,the animals underwent the same anesthesia but without any operative procedures.At 24h after surgery,blood and terminal ileum were sampled.The serum D-lactate levels were determined using an ELISA kit.The intestinal permeability was determined by measuring the intestinal clearance of FITC-Dextran(FD4).The intestinal tight junction proteins(ZO-1 and occludin)were measured by Western Blot.Results:Both serum D-lactate level and intestinal permeability were increased after peritoneal air exposure,which were proportional to the time length of peritoneal air exposure.Serum D-lactate level in groups with peritoneal air exposure for 2 and 3h,intestinal permeability in the group with peritoneal air exposure for 3h,were significantly increased(p<0.05)when compared with the control group.The intestinal tight junction proteins(ZO-1 and occludin)had an opposite tendency.The intestinal tight junction proteins(ZO-1 and occludin)in the group with peritoneal air exposure for 3h were significantly decreased(p<0.05)when compared with the control group.Conclusion:Peritoneal air exposure could induce damage to the intestinal mucosal barrier,which was proportional to the time length of peritoneal air exposure.Part ?Study I Dynamic intestinal motility changes after peritoneal air exposureObjective:To assess dynamic intestinal motility changes after peritoneal air exposure for different time.Methods:Thirty Sprague-Dawley rats were randomized into five groups(6/group):a control group,a sham group,and three exposure groups with peritoneal air exposure for 1,2,and 3h,respectively.For the exposure groups,rats received a 3cm midline abdominal incision,and then the wound edge was retracted to allow for maximal peritoneal air exposure for 1,2,and 3h,respectively.Thereafter,the abdomen was closed in one layer with 3-0 silk continuous suture.For the sham group,the animals underwent the same anesthesia and operation procedure but without laparotomy.For the control group,the animals underwent the same anesthesia but without any operative procedures.At 24h after surgery,intestinal motility was assessed by charcoal transport.Results:The intestinal charcoal transit rate was decreased after peritoneal air exposure,which was proportional to the time length of peritoneal air exposure.Compared with the control group,groups with peritoneal air exposure for 2 and 3h showed a significant decrease in the intestinal charcoal transit rate(p<0.05).Conclusion:Peritoneal air exposure could induce a decrease in intestinal motility,which was proportional to the time length of peritoneal air exposure.Study ? Effect of peritoneal air exposure on intestinal inflammatory responseObjective:To investigate the changes in intestinal inflammatory response after peritoneal air exposure for different time,and to study the possible mechanism for intestinal motility dysfunction after peritoneal air exposure.Methods:Thirty Sprague-Dawley rats were randomized into five groups(6/group):a control group,a sham group,and three exposure groups with peritoneal air exposure for 1,2,and 3h,respectively.For the exposure groups,rats received a 3cm midline abdominal incision,and then the wound edge was retracted to allow for maximal peritoneal air exposure for 1,2,and 3h,respectively.Thereafter,the abdomen was closed in one layer with 3-0 silk continuous suture.For the sham group,the animals underwent the same anesthesia and operation procedure but without laparotomy.For the control group,the animals underwent the same anesthesia but without any operative procedures.At 24h after surgery,intestinal motility was assessed by charcoal transport,and then blood and terminal ileum were sampled.Serum and intestinal tumour necrosis factor(TNF)-?,interleukin(IL)-1?,IL-6 and IL-10 concentrations were measured by ELISA,and gene expression of intestinal TNF-?,IL-1?,IL-6 and IL-10 was also assessed by real time polymerase chain reaction(RT-PCR).Results:The serum and intestinal TNF-?,IL-1?,IL-6 and IL-10 levels were increased after peritoneal air exposure,which were proportional to the time length of peritoneal air exposure.Except the serum IL-1? level,the levels of other inflammatory cytokines in the group with peritoneal air exposure for 3h were all significantly increased(p<0.05)when compared with the control group(p<0.05).Meanwhile,the gene expression of intestinal TNF-?,IL-1?,IL-6 and IL-10 had a similar tendency,with significance in groups with peritoneal air exposure for 2 and 3h(p<0.05).Conclusion:Peritoneal air exposure could induce an increase in systemic and intestinal inflammation,which was proportional to the time length of peritoneal air exposure.The intestinal inflammation may be a major cause of the decreased intestinal motility induced by peritoneal air exposure.Part ?Intervention study on lipid enriched enteral nutrition reducing intestinal injury after peritoneal air exposureStudy ? Protective effect of lipid enriched enteral nutrition on intestinal mucosal barrier after peritoneal air exposureObjective:To study the protective effect of lipid enriched enteral nutrition on intestinal mucosal barrier after peritoneal air exposure.Methods:Twenty-four Sprague-Dawley rats were randomized into four groups(6/group):a control group(CG),a peritoneal air exposure group(PG),and a standard enteral nutrition group(peritoneal air exposure plus standard enteral nutrition,SEN),and a lipid enriched enteral nutrition group(peritoneal air exposure plus lipid enriched enteral nutrition,LEN).According to the results in Part I of this project,we chose peritoneal air exposure for 3 h as the model for peritoneal air exposure in this study.Rats in SEN group and LEN group received standard enteral nutrition and lipid enriched enteral nutrition respectively via gavage at 12h(3mL;other time points were all 0.75 mL),2h,45min before peritoneal air exposure,and at 45m,90m,3h after peritoneal air exposure.Rats in CG group and PG group received equal amounts of saline by the same way as control.At 24h after surgery,blood and terminal ileum were sampled.The serum D-lactate levels were determined using an ELISA kit.The intestinal permeability was determined by measuring the intestinal clearance of FITC-Dextran(FD4).The intestinal tight junction proteins(ZO-1 and occludin)were measured by Western Blot.The histopathology and the ultra microstructure were also examined using light microscope and transmission electron microscope respectively.Results:Compared with CG group,PG group showed a significant difference in the above indicators(p<0.05);however,LEN group showed a significant improvement in some indicators when compared with SEN group,although the two nutritional group have different degrees of improvement in the indicators.Compared with SEN group,LEN group showed a significant decrease in serum D-lactate and a significant increase in intestinal tight junction protein ZO-1(p<0.05).The results in the histopathology and the ultra microstructure further revealed that LEN group showed a significantly decreased Chiu's scores(p<0.05),indices for intestinal mucosal injury,and a ultra microstructure improvement including small tight junction gap,increased desmosome,and regular microvilli.Conclusion:Lipid enriched enteral nutrition could improve intestinal mucosal barrier damage induced by peritoneal air exposure.Study ? Enhancement effect of lipid enriched enteral nutrition on intestinal motility after peritoneal air exposureObjective:To investigate the effect of lipid enriched enteral nutrition on intestinal motility,and to study the related mechanism.Methods:Twenty-four Sprague-Dawley rats were randomized into four groups(6/group):a control group(CG),a peritoneal air exposure group(PG),and a standard enteral nutrition group(peritoneal air exposure plus standard enteral nutrition,SEN),and a lipid enriched enteral nutrition group(peritoneal air exposure plus lipid enriched enteral nutrition,LEN).According to the results in Part II of this project,we chose peritoneal air exposure for 3h as the model for peritoneal air exposure in this study.Rats in SEN group and LEN group received standard enteral nutrition and lipid enriched enteral nutrition respectively via gavage at 12h(3mL;other time points were all 0.75 mL),2h,45min before peritoneal air exposure,and at 45m,90m,3h after peritoneal air exposure.Rats in CG group and PG group received equal amounts of saline by the same way as control.At 24h after surgery,intestinal motility was assessed by charcoal transport,and then blood and terminal ileum were sampled.Serum and intestinal TNF-?,IL-1?,IL-6 and IL-10 concentrations were measured by ELISA,and gene expression of intestinal TNF-?,IL-1?,IL-6 and IL-10 was also assessed by RT-PCR.Results:Compared with CG group,PG group showed a significant difference in the above indicators(p<0.05);however,LEN group showed a significant improvement in some indicators when compared with SEN group,although the two nutritional group have different degrees of improvement in the indicators.Compared with the SEN group,LEN group showed a significant increase in intestinal charcoal transit rate,a significant decrease in serum and intestinal TNF-? and IL-6,and a significant increase in serum and intestinal IL-10.Meanwhile,LEN group also showed a significant decrease in the gene expression of intestinal TNF-?,IL-1? and IL-6,and a a significant increase in the gene expression of intestinal IL-10 when compared with the SEN group(p<0.05).Conclusion:Lipid enriched enteral nutrition could improve intestinal dysmotility induced by peritoneal air exposure.This intestinal motility improvement may be related to the reduced intestinal inflammation induced by lipid enriched enteral nutrition.Conclusions Based on the results from the above three parts,we concluded that:1.Peritoneal air exposure could induce damage to the intestinal mucosal barrier,which was proportional to the time length of peritoneal air exposure;2.Peritoneal air exposure could induce a decrease in intestinal motility and an increase in intestinal inflammation,which were proportional to the time length of peritoneal air exposure;3.The intestinal inflammation may be a major cause for the decreased intestinal motility induced by peritoneal air exposure;4.Lipid enriched enteral nutrition could improve intestinal mucosal barrier damage induced by peritoneal air exposure;5.Lipid enriched enteral nutrition could improve intestinal dysmotility induced by peritoneal air exposure;6.The improvement effect of lipid enriched enteral nutrition on intestinal motility after peritoneal air exposure may be related to the reduced intestinal inflammation. |
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