Effects Of Hypoxic Preconditioning On Neurological Symptoms And Cerebral Edema After Traumatic Brain Injury In Rats

Traumatic brain injury is a common disease which has a high mortality rate and disability rate.Traumatic brain injury often leads to severe brain edema.The brain edema is closely related to the treatment and prognosis of Traumatic brain injury. Hypoxic preconditioning as an endogenous mechanism of the organizations has many protective effects. A lot of enlightenments in clinical medicine, high altitude medicine, aviation medicine and sports medicine would be got from it`s further study.Objective: To observe the effects of hypoxic preconditioning on the neurological symptoms,water content and ion content of brain after Traumatic brain injury in rats.So as to further discuss the cerebral protective effects of hypoxic preconditioning.Methods: Totally 180 male Wistar rats were randomly divided into three groups:Sham Operation Group(SO)(n=60), Traumatic Brain Injury Group(TBI) ( n=60 ) and Hypoxic Preconditioning Group(HP)(n=60).The rats in TBI group were made into brain injury model in the way of fluid percussion brain injury with the pressure of 300kPa. The rats in HP group were given a hypoxic preconditioning before made into the fluid percussion brain injury .Then test the scores of behavior and collect the brains of rats at different times (4h,8h,24h,72h,5d,7d). Measure the water content of brain by wet and dry weight method. And measure the content of sodium ion and potassium ion by Atomic absorption spectrophotometry.All datas were analysised statistically with variance analysis and q test. Results:The rat model with fluid percussion brain injury were successfully maded.1. Pathological changeNo significant change in Sham Operation Group. Various degrees of cortex injury and the subarachnoid hemorrhage can be observed after the Traumatic brain injury. At the early stage of TBI (<24h)some of the neurocytes became swelling and vacuolization. At the middle stage(72h~5d) necrosis neurocytes and glial cells increased. At the late stage glial cells conspicuously increased and brain edema gradually reduced.2.The scores of behaviorThere were no significant differences (P>0.05) among the scores of subgroup in SO group. The scores were decreased at the 4h,the nadir of scores appeared at 24~72h after TBI, and began to increase at 5d ,went back to normal levels at 7d compared with SO group. The degree of the change of scores in HP group was significantly less than that in TBI group(P<0.05).3. Water and ion contentThere were no significant differences (P>0.05) between the water and ion content of subgroup in SO group. The water content was increased at the 4h,the peak value appeared at 24~72h after TBI, and began to decline at 5d ,went back to normal levels at 7d compared with SO group (P>0.05). The degree of increase of content in HP group was significantly less than that in TBI group(P<0.05).The change of sodium ion content was in parallel with the content of water, but the change of potassium ion content was opposite. Conclusions:1. The behavior score changes: Animal behavior scores were decreased at the 4h,the nadir of scores appeared at 24~72h after TBI, and began to increase at 5d ,went back to normal levels at 7d.2. The changes of brain edema related factors after Traumatic brain injury in rats: The water content began to increase at 4h, peaked at 24 hours, went back to normal levels at 7d. The change of sodium ion content was in parallel with the content of water, but the change of potassium ion content just on the opposite.3. The behavior scores, water content, sodium ion content and potassium ion content of TBI and HP group have the same varying tendency.4. The degree of the change of HP group was smaller than TBI group. Hypoxic preconditioning can alleviate brain edema, and raise animal neurobehavioral scores after injury.