Short Term And Long Term Effects Of Inhibition Of HIF-1 And Activation Of Wnt Signaling Pathway On Brain Injury In Preterm Infants

Objective Premature white matter damage(WMD)is the main pathological manifestation of premature infants with hypoxic ischemic brain damage.The experiment constructed animal model of premature WMD,then injected the PHI(inhibitor of hypoxia inducible factor-1 alpha)in 3 day old rats which have already got the hypoxic ischemic brain damage after 24h,and the activated the Wnt signaling pathway.What to do next is:to observe the number of Oligodendrocyte precursor cells(OPC)and oligodendrocytes(OL);and to measure the content of HIF-1 alpha and the expression of the key factor in the Wnt signal pathway(Wnt7a);then do a follow up study about the behavior,cognition and memory ability of the rats when they are 28 days old.Methods Take some SD rats which are 3 days old,and then randomly divide them into four groups:WMD,WMD+PHI,WMD+PHI+Wnt,WMD+PHI+XAV939,Construct the model of WMD,and after 24 hours inject different reagents(depend on different groups)by using ventricular localization technique.First,number the quantity of OPC and OL in D1,D3,D7,D14 brain tissues by using the method of immunofluorescence,OPC was performed with 01 single standard,OL was performed with 04 single standard.Then measure the expression of the protein which is named HIF-1 alpha in D1,D3,D7,D14 brain tissues of rats by the technology of Western blot.And then measure the expression of HIF-1 alpha and Wnt7a in D1,D3,D7,D14 brain tissues of rats by using RT-qPCR technique.At last,when the rats become 28 days old,we use suspension test,open field test and dark avoidance test to check the behavior,cognition and memory ability of them.Results The number of OPC and OL in the group of WMD was the least,and the number of OPC and OL in the group of WMD+PHI+Wnt agonist was significantly higher than that of the other three groups.Just the same trend as immunofluorescence,during different time point,the quantity of HIF-1 alpha was the lowest in the group of WMD,and the group of WMD+PHI+Wnt agonist was the highest.And the results indicate the expression of HIF-1 was positively correlated with the expression of Wnt7a(r=0.765,p<0.05).The behavioral experiment suggested that there is no difference in muscle movement between the rats.And PHI may have some protective effect on rat emotion cognition and memory ability,especially applying the PHI with Wnt agonist together.Conclusion When 3 days old rats get immature cerebral white matter injury,we can use the PHI with Wnt agonist together,that can effectively reduce the damage of OPC,and reduce loss of OPC,and can also promote the proliferation of OPC.When recover from the hypoxia environment,there will be more OPC to participate in the differentiation of OL,and can promote the construction of myelination,maintain the function of the central nervous system stabilization,so that can repair part of brain injury in preterm infants.