Effect Of Simulated Acute Plateau Hypoxia On Intestinal Mucosa Injury And Hypoxia-related Protein In Rats

Objective: To observe the effect of simulated acute plateau hypoxia on intestinal mucosa injury and hypoxia-related protein EPAS1,EGLN1 and PPARA in rats at different altitudes and time-point,explore the influence of simulated acute plateau hypoxia on intestinal mucosa injury and mechanism of hypoxia-related protein in injury.Methods: The wistar rats were used as research subjects.Different altitudes and timepoint high altitude hypoxic animal model were established by low pressure oxygen chamber.Rats were randomly divided into control group(n=8),3000 m group(n=24),4500 m group(n=24),6000 m group(n=24).Then,each test group were divided into hypoxia 24 h subgroup,48 h subgroup,72 h subgroup.The hypoxia component of the plateau was hypoxia 24 h subgroup(n=8),plateau hypoxia 48 h subgroup(n=8),and plateau hypoxia 72 h subgroup(n=8).The hypoxia groups were put at different altitude in large-scale hypobaric chamber.After the model was established,histopathologic changes were observed with HE staining.IHC,RT-PCR,and Western Blot were used to detect the expression of hypoxia-related proteins EPAS1,EGLN1,and PPARA in the acute hypoxia model.Results:(1)At different altitudes(3000m group,4500 m group and 6000 m group)and time-point(24h subgroup,48 h subgroup,72 h subgroup)high altitude hypoxic animal model,HE showed: in the plateau group,intestinal villi appeared edema,shedding,disordered arrangement,thinning of the intestinal wall,and even separation of the epithelial layer from the intrinsic layer on both sides of the intestinal villi.The degree of damage increases with the increase of altitude and the prolongation of hypoxia.(2)Analyzing the expression of hypoxia related proteins EPAS1,EGLN1,and PPARA at different time-point under the same altitude,IHC displayed : EPAS1 and EGLN1 were barely expressed in the intestinal epithelial cells of the control group and were expressed in epithelial cells of the plateau group and inflammatory cells(lymphocytes and macrophages)of the intestinal tissues.PPARA was weakly expressed in the intestinal epithelial cells in the control group,and was significantly positive in the plateau group.The cytoplasm was brownish or brownish yellow and occasionally expressed in the nucleus.The results showed that: At the same altitude of 3000 m group,there was no significant difference between the 24 h subgroup and 48 h subgroup,and the difference between 48 h subgroup and 72 h subgroup was statistically significant(P<0.05);at the same 4500 m group,24 h subgroup,48 h subgroup,72 h subgroup had statistically significant differences between the two groups,and 72 h subgroup> 48 h subgroup> 24 h subgroup> control group(P <0.05);the same 6000 m group,hypoxia 24 h subgroup,48 h subgroup was statistically significant(P <0.05),there was no statistical difference between hypoxia 48 h subgroup and 72 h subgroup.(3)Analyzing the expression of hypoxia related genes EPAS1,EGLN1,and PPARA at different altitude under the same time-point,RT-PCR explained: Under the same hypoxia 24 h subgroup,there was no statistical difference between 3000 m group and 4500 m group.The 4500 m group and 6000 m group were statistically different(P<0.05).In the same hypoxia 48 h subgroup,mRNA expressions of 3000 m group,4500 m group,and 6000 m group were sequentially expressed.Enhancement,namely 6000 m group> 4500 m group> 3000m> control group(P<0.05);under the same hypoxia 72 h subgroup,3000 m group,4500 m group had statistically significant differences(P<0.05),4500 m group,6000 m group had no statistical difference.(4)Analyzing the expression of hypoxia related proteins EPAS1,EGLN1,and PPARA,Western Blot demonstrated: At the same altitude of 4500 m group,the expression of proteins at different time points increased in proper order,namely,72 h subgroup> 48 h subgroup> 24 h subgroup> control group(P<0.05);in the same hypoxia 48 h subgroup,The expression of hypoxia-related proteins at different altitude increased in proper order,namely,6000 m group> 4500 m group> 3000m> control group(P<0.05).Conclusion: Plateau hypoxia has an injurious effect on rat intestinal mucosa.Hypoxiarelated proteins EPAS1,EGLN1,and PPARA play a direct and important role in the pathogenesis of hypoxic injury.Hypoxia-related proteins EPAS1,EGLN1,and PPARA are present in plateau hypoxic intestinal epithelium.Expression in tissues was positively correlated with altitude and hypoxia.Altitude and hypoxia time were the main factors affecting the intestinal epithelial injury and the expression of hypoxia related proteins EPAS1,EGLN1 and PPARA.