The Effect Of Hyperbaric Oxygen On Early Cerebral White Matter Injury In SAH Rat Model

Objective:Establishing a rat model of subarachnoid hemorrhage(SAH)and adopting hyperbaric oxygen therapy(HBO)to observe the effects of HBO on early white matter injury(WMI)and neurological function recovery after SAH,which can provide experimental basis for HBO treatment of WMI after SAH.Methods:Seventy Sprague-Dawley female rats(SD female rats)were randomly divided into blank control group(n=10),the 24h after sham operation group(n=10),the 72h after sham operation group(n=10),the 24h after SAH model group(n=10),the 72h after SAH model group(n=10),the 24h after SAH+HBO group(n=10),and the 72h after SAH+HBO group.There are 7 groups in total.Among them,the blank control group had no treatment;the sham operation groups were only drilled holes in the skull(harnpan);the last 4 groups were injected with blood in the cisterna chiasmatica to prepare a rat SAH model;and the SAH+HBO groups were treated with hyperbaric oxygen after 4-6h from successful modeling and were treated twice a day.Then,at corresponding time points(24h or 72h),the rats were scored for neurological function of mNSS.And the rats were killed to collect the white matter on both sides adjacent to the hematoceles in the prechiasmatic cistern.After that,special silver staining was used to observe axon and medullary sheath injury;and TUNEL staining was used to detect Glial cells Apoptosis;immunohistochemistry and western blotting were used to detect the expression of axon injury markers(β-APP and NG2)and myelin protein markers(MBP)in brain tissues.IBM SPSS Statistics 23.0 statistical software was used to analyze the data.Results:1.The mNSS score of SAH groups was higher than that of sham operation groups at each time point,and the difference was statistically significant(P<0.05);mNSS score in SAH+HBO groups was lower than that in SAH groups at each time point,and the difference was statistically significant(P<0.05).There was no significant difference in mNSS scores between the sham operation groups and the blank control group at each time point(P>0.05).2.The special silver staining of brain tissue under microscope showed that the axons and nerve fibers of neurons in the normal control group and the sham operation groups were slender black strips.In SAH groups,axon fracture and nerve fibre aggregation and winding were observed.In SAH+HBO groups,axon injury was also observed but the degree was less than that in SAH groups.3.The number of apoptosis in SAH groups was higher than that in sham groups at each time point,and the difference was statistically significant(P<0.05).The number of apoptosis in SAH+HBO groups at each time point was lower than that in SAH groups,and the difference was statistically significant(P<0.05).There was no significant difference in the number of apoptotic cells between sham operation groups and blank control group at each time point(P>0.05).4.The positive rates of β-APP and NG2 in SAH groups at each time point were higher than those in sham operation groups;and the MBP was lower than that in sham operation groups,and the difference was statistically significant(P<0.05).The positive rates of β-APP and NG2 in SAH+HBO groups were lower than those in SAH groups,and the positive rates of MBP were higher than those in SAH groups,and statistical difference was significant(P<0.05).However,there was no significant difference between the blank control group and the sham groups(P>0.05).5.Western blotting showed that the expression trends of NG2,β-APP and MBP were consistent with the immunohistochemical changes,and the differences were statistically significant(P<0.05).There was no significant difference between the control group and the sham groups(P>0.05).Conclusion:HBO can alleviate early WMI after SAH and improve neurological dysfunction in SAH rats.