The Effects Of Glutamine On Intestinal Barrier In Cirrhotic Rats

Objective:To investigate the effect of glutamine(GLN)on intestinal barrier of cirrhotic rats and try to elicit its mechanism.Methods:Fifty male Wistar rats,weighing 220～250g,were randomly assigned into 5 groups:as normal groups(NC),models of cirrhosis including 6 weeks(M6)and 10 weeks(M10)subgroups, cirrhosis plus glutamine groups which also had 6 weeks(M6+GLN)and 10 weeks(M10+GLN) subgroups.Except normal group which was feed with normal food and tap water,the other four groups was treated with CCl₄ plus alcohol to induced cirrhosis.Prior to the 6- and 10-week time point,the M+GLN groups were gavaged with glutamine as 1.0 gram.kg^-1once a day for three weeks.Histological examination including microscope and transmission electron microscope were carried after liver and intestinal tissues staining with haematoxylin-eosin(HE)and vangieson(VG).Both peripheral and portal Endotoxin(ET)and Diamine oxidase(DAO)were assayed.So were plasma alanine aminotransferase(ALT),albumen(ALB)and tumor necrosis factor-alpha(TNF-α).And the intestinal homogenate nitrogen monoxides(NO)and hepatic homogenateγ-glutamylcysteinylglycine(GSH)were examined in different groups.Result:1.The modeling of cirrhosis rats:the HE and VG staining of liver tissues showed that M6 had prominently fibrosis and M10 severely cirrhosis.2.Evaluation of intestinal barrier functions2.1 The pathological changes of intestinal under the microscope and transmission electron microscope:There were no pathological changes in intestinal in normal rats.But under the microscope,high-density inflammatory cells were migrating into colonic submucous and its villus were edema and desquamation in M6 and M10 groups.At the transmission electron microscope the microvillus of M10 were fewer and shorter and the epithelia junctions were widener than M6 groups.At the same time microvillis of absorptive cells and goblet cells were fewer and shorter or lodging,abruption.Mitochondria of epithelia and absorptive cells intumesced,their cristaes abrupted and deficited or deflexed.The karyopyknosis, heterochromatin margination were also observed.The changes of M+GLN groups were much lighter than M groups.2.2 Endotoxin and DAO in serum:The M group had higher level than N and M+GLN groups. There were significantly higher level both serum endotoxin and DAO between M and N(p＜0.05),also the M and M+GLN(p＜0.05).After administration glutamine the endotoxin and DAO levels were decreased prominently,and there were significantly difference between M10+GLN and M10 groups(p＜0.05). 3 Intestinal Endotoxemia:the levels of peripheral plasma endotoxin in cirrhosis model groups and model plus glutamine groups were higher than normal groups(p＜0.05).This result showed that IETM were occurred during the course of the study.The difference of endotoxemia was significant between M10 and M6 groups(p＜0.05).Compared with model groups,the endotoxin was decreased in M+ GLN groups.4 Changes of NO in intestinal and serum TNF-α:the expression of NO and TNF-αin cirrhosis model and cirrhosis plus glutamine were higher than in normal group(p＜0.05).And the difference was significant between M6 and M10(p＜0.05).After glutamine gavaged the expression of NO and TNF-αwere more lower than the model(p＜0.05).5 Liver GSH and serum ALT and ALB:There were higher level of liver GSH and serum ALB in the two model groups compared with the normal group,and the difference was significant between M6 and M10(p＜0.05).The liver GSH in M10 is lower than M10+GLN(p＜0.05).The serum ALT of M10 reached highest lever and there were differences between M6 and M10(p＜0.05).6 Apoptosis of intestinal epithelia:The index of apoptosis of intestinal epithelia was gradually heightened in NC,M6 and M10 groups(p＜0.05 for N vs.M and M6 vs.M10).Compared to the cirrhosis groups,the cirrhosis plus glutamine lowered the index of apoptosis apparently (p＜0.05 both M6 vs.M6+GLN and M10 vs.M10+GLN).There were significantly difference between M and NC(p＜0.05),M6 and M10(p＜0.05),M6 and M6+GLN(p＜0.05),M10 and M10+GLN(p＜0.05).7 The correlation analysis:The negative correlation was found between liver GSH and serum ALT(r=-0.69,p＜0.01),peripheral endotoxin and serum ALB(r=-0.65,p＜0.01).There were positive correlation between peripheral endotoxin and serum ALT(r=0.88,p＜0.01), peripheral endotoxin and serum TNF-α(r=0.66,p＜0.01),peripheral endotoxin and intestinal NO(r=0.81,p＜0.01),the apoptotic index of intestinal and portal endotoxin(r=0.81,p＜0.01) and the apoptotic index of intestinal and intestinal NO(r=0.74,p＜0.01).Conclusion:1,Our data showed that IETM was occurred both in 6 and 10 weeks of cirrhotic models,and glutamine was beneficial to lowering IETM by protecting intestinal barrier and reducing NO and TNF-α.2,Apoptosis might be one of the mechanisms of intestinal barrier dysfunction and glutamine could effectively protect the barrier of intestinal by decreasing epithelia apoptosis.3,Glutamine could preventthe further liver injury in cirrhotic rats through increasing the liver GSH.