| Objective:To observe the change of the permeability of blood-brain barrier after traumatic brain injury in rat and to investigate the impact of the permeability of blood-brain barrier and cognitive capacity after traumatic brain injury in rat by the increased number of endothelial progenitor cells in peripheral circulation.Methods:450 healthy adult Wistar rats were randomly divided into control group, sham group, TBI group and treatment group. The model of traumatic brain injury used by hydraulic blow. The rats of treatment group were gotten intraperitoneal injection of G-CSF (50 ug·kg-1·d-1) for 5 days before injury, and the models were replicated in 2 days after stopping injection. EB quantitative detection of cortex and hippocampus was gotten through detecting the optical density of sample, and Evans blue content was inquired from standard curve and equation, then the results were worked out. EB tracing of brains was observed under fluorescence microscope. Brain water content was determinated in wet and drying weight way. Endothelial progenitor cells were marked by CD34/CD133 double positive cells and measured by flow cytometry. CD34+ micro vessel density was detected by immunohistochemical method. Morris water maze was applicated to evaluate cognitive function.Results:1 The changs of BBB permeability after traumatic brain injury in rats:The EB content of cortex and hippocampus in injury side in TBI group was significantly higher compared with the control group at 2h after injury (P<0.05), and reached the peak at 4h, and begained to decline at 6h and to the lowest at 12h (still significantly higher than the control group, P<0.05), and increased again at 24h and reached the second peak at 72h, and significantly was lower in cortex than 4h(P<0.05), but was not significantly different in hippocampus at 4h, and declined again at 120h, and approached to the control group at 168h (P>0.05).2 The influence of Granulocyte colony stimulating factor on BBB permeability of cortex and hippocampus after brain injury in rat:Compared with TBI group, the EB content of cortex and hippocampus in treatment group was no significant difference at 2h,4h,6h and 12h after TBI (P> 0.05), and lower than the TBI group at 24h,72h and 120h after TBI (P<0.05); 3 The regults of EB tracer of rat brain tissue slices observed under fluorescence microscopy: The red fluorescent granules was obvious in TBI group at 2h after TBI, and deepened at 4h, and thin at 6h, and thinest at 12h, and deepened again at 24h, and the second peak occurred at 72h, and thin again at 120h, and approached to the control group at 168h. Compared with TBI group, the red fluorescence of treatment group was decreased significantly at 24h,72h,120h after TBI.4 Changes of brain water content: Compared with the control group, the brain water content in treatment group increased at 2h after injury (P<0.05), and gradually rised at 4-24h, and peaked at 72 h, and decreased at 120h, and returned to normal at 168h. Compared with TBI group, the brain water content in treatment group was lower at 24-120h group (P<0.05).5 The changes of EPCs in peripheral circulation in rats:Compared with the control group, EPCs in peripheral circulation in TBI group decreased significantly at 2 h after injury (P<0.05), and began to rise at 4h, and increased significantly at 6～12 h compared with the control group (P<0.05),24 h decreased, and closed to the normal level at 72 h. EPCs in peripheral circulation in treatment group was significantly increased compared with TBI group at 2 h～72 h after injury (P<0.05), and closed to the normal level at 120 h after in injury.6 CD34+microvessel density test results: CD34+ microvessel density of cortex and hippocampal dentate gyrus increased in TBI group at 72 h after injury, and were significantly different compared with the control group (P<0.05), and continued to 168 h. CD34+ microvessel density increased in treatment group at 24 h after injury, reached the peak at 72 h, and increased significantly compared with the TBI group (P<0.05), and continued to 168h.7 The results of oriented navigation test:Compared with control group, the escape latency and swimming distance extented significantly in the training of 1-5 day in TBI group (P<0.05). Compared with TBI group, the escape latency and swimming distance in the training of 1-5 day in treatment group shortened significantly (P<0.05).8 The results of space exploration test:Compared with the control group, the percentage of target quadrant if TBI group decreased (P<0.05) significantly. Compared with TBI group the percentage of target quadrant of treatment group was increased significantly (P<0.05).Conclusion:1 BBB opening exists in the injury cortex and hippocampus in rats after TBI, and BBB opening was biphasic.2 The destruction of BBB and increased brain water content in rats is one of the important factors leading to secondary brain injury after TBI.3 EPCs involve in BBB repair after TBI. the increased EPCs in peripheral circulation can repair the BBB and reduce brain edema.4 The increased permeability of BBB and brain water content after TBI result in secondary brain injury which is an important reason of cognitive dysfunction.5 Increasing the number of EPCs in peripheral circulation can repair BBB and decrease brain edema in rats after TBI, then reduce secondary brain injury, thereby improve the cognitive dysfunction. |
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