Expression Changes of Hypoxia-inducible Factor-1 α and Aquaporin-4 in Brains of Rats after Cardio-pulmonary Resuscitation and the Intervention Effects of β-aescine Sodium
|School||Dalian Medical University|
|Keywords||cardio-pulmonary resuscitation Brain edema aquaporin-4 hypoxia-inducible factor-1α β- aescine Sodium|
Objective:To study the expression changes of hypoxia-inducible factor-1αand aquaporin-4 in brains of rats after cardio-pulmonary resuscitation, hypoxic-ischemic brain damage, and effects ofβ-aescine Sodium on expression of hypoxia-inducible factor-1α(HIF-1α)and aquaporin-4(AQP4), and protective effect ofβ-aescine Sodium on the nerve cells in brain.Method:One hundred and 180 healthy male Sprague-Dawley rats, weighing 220-250g, were randomly divided into sham operated group, model group of cardio-pulmonary resuscitation(HIBD)and treatment group ofβ-aescine Sodium. According to different time of putting to death, every group was divided into six subgroups:1h、3h、6h、12h、24h、48h. There were 5 rats in each subgroup. The treatment group were given with intraperitoneal injection withβ-aescine Sodium(0.4mg/kg) immediately after cardio-pulmonary resuscitation, administered per 12 hours. The equal volume of normal saline was given in sham operated group and model group in corresponding time point (Note:according to urinary volume, giving the equal volume of normal saline to rats of each group). After animals woke up, we put them back to the rat’s cage. To observe vital signs and nervous symptoms of rats after operation. According to different time points, inserted the needle from cardiac apex to left ventricle in every rat, and reached to aortic root. Make a small cut in the right auricle. First normal saline was perfused rapidly, until clear liquor flew out. 4% paraformaldehyde (100ml) were perfused rapidly, then 200ml were perfused slowly. After perfusion, cut off the head immediately, opened the skull, and took out the brain tissues. Immunohistochemistry method was used to detect AQP4 and HIF-1α. And analyzed the slices . The results were divided into 5 grades:unstained:negative(-);light yellow: weak positive(+);yellow: positive(++);brown yellow: middle positive(+++);dark brown yellow: strong positive(++++).At the same time, applying the light microscope, whose amplification multiple was 400 times, 5 different visual field were randomly chose, and type stratagene EagleEeyⅡimage analytical processing system was applied to analyzed quantitatively. According to Eliott formula, moisture content of partial brain tissue of one side hemisphere was calculated in each subgroup. The other part of brain tissue was preserved cryogenically. qRT-PCR was used to detect tlle mRNA expressions of AQP4 and HIF-1α.Results:model group of cardio-pulmonary resuscitation was built through suffocation. The test results of moisture content and AQP4 at different periods of time suggested that moisture content of brain tissue was increased obviously in model group of cardio-pulmonary resuscitation, and brain edema reaction was obvious, especially serious at 6h. Moisture content decreased after 12h. brain edema reaction gradually reduced, and the expression of hypoxic—ischemic AQP4protein of brain tissue was up regulated. The test results of immunohistochemistry and RT-PCR of AQP4 and HIF-1αin brain tissue of rats at different periods of time suggested that the expressions of AQP4 and HIF-1αwere negative in sham operated group, and were up regulated in model group of cardio-pulmonary resuscitation. In model group of cardio-pulmonary resuscitation , AQP4 peaked at 6h, and immunohistochemistry showed positive(+++), the expressions of AQP4 decreased gradually after 12h. HIF-1αpeaked at 6h, and then dropped, and immunohistochemistry at 6h showed strong positiv(e++++). Compared to in model group of cardio-pulmonary resuscitation, the extent of brain edema and the expression of AQP4 fell back with varied degrees in different detective time and the expression of HIF-1αincreased in the treatment group ofβ-aescine Sodium.Conclusion:The moisture content of brain tissue was increased and the expression of AQP4 and HIF-1αwere stronger after cardio-pulmonary resuscitation. AQP4 and HIF-1αinvolved in the occurence and development of brain edema which resulted from hypoxic-ischemic brain damage.β- aescine Sodium inhibited the expression of AQP4 and increased the expression of HIF-1α, so then inhibited occurence and development of brain edema after cardio-pulmonary resuscitation, and reduced injury of peripheral issues which resulted from brain edema, so then protected the nerve cells in brain, and promoted the recuperation of brain function.