Effect Of Hyperbaric Oxygen On The Neural Stem Cell Proliferation Migration And Differentiation In Dentate Gyrus Subgranular Zone After Transient Focal Cerebral Ischemia In The Adult Rats

Objective:To investigate the effect of hyperbaric oxygen at different time on the neural stem cell proliferation, migration and differentiation in dentate gyrus subgranular zone after transient focal cerebral ischemia in the adult rats, so as to explore the neuroprotection of hyperbaric oxygen therapy.Methods:60Sprague-Dawley adult rats were randomly distributed into sham control group, transient middle cerebral artery occlusion (tMCAO) group, hyperbaric oxygen group, hyperbaric air group and normobaric oxygen group. Each group was randomly distributed into2day,3day,7day and14day subgroups. Each subgroup had3animals. After middle cerebral artery occlusion (tMCAO) for80min, rats were subjected to reperfusion. Each group started therapy at2h after occlusion. Hyperbaric oxygen (2.5ATA,100%oxygen,60min), hyperbaric air (2.5ATA, air,60min), normobaric oxygen (1ATA,100%oxygen,60min), each animal accepted corresponding therapy once a day except tMCAO group and sham control group, until the ends of each time point. BrdU abdominal injection on the first and the second day after surgery to label the newborn cells.The first labeling was after the first therapy, once per4hours,3times a day, totally2days. Fluorescent double-label immunohistochemistry was to exam the newborn cells and their phenotypes in bilateral dentate gyrus SGZ。 Result:1. The number of the proliferation neural stem cells (BrdU+/nestin+) in HBO group had significantly increased in2day,3day in ischemic side and7day in bilateral (P<0.05) compared with the other four groups. The number of the neural stem cells in HBO group is at the peak of3day.2. Differentiated immature neurons (BrdU+/DCX+) were born from the proliferation neural stem cells. Both the ischemic side and non-ischemic side in HBO group had significantly increased in2day (non-ischemic side),3day (ischemic side),7day and14day (bilateral)(P<0.05) compared with the other four groups. The number of the immature neurons in HBO group is at the peak of7day.3. Differentiated astrocytes (BrdU+/GFAP+) were born from the proliferation neural stem cells. The number of the astrocytes in HBO group had no significant difference compared with other four groups on2day,3day,7day and14day (non-ischemic side)(P>0.05), and on2day and14day (ischemic side)(P>0.05). On3day sham control group and on7day hyperbaric air group (ischemic side) both had significantly increased compared with other four group (P<0.05).Conclusion:Hyperbaric oxygen promotes neutral stem cell in dentate gyrus subgranular zone proliferation, differentiation into neuron but astrocyte, and migration into granular layer in rats subjected to transient MCAO. The life span of the newborn neuron could last at least2weeks.