The Study On The Correlation Between The Expression Of HIF-1 α And VEGF In Drowning Rats Brain Injury Caused By Freshwater Drowning

ObjectiveTo observe the condition of brain injury caused by freshwater drowning following the establishment of the animal model by freshwater drowning. To research the relationship between the expression of hypoxia inducible factor - alpha (HIF- α) and vascular endothelial growth factor (VEGF) in drowning rats brain and brain injury caused by freshwater drowning, meanwhile, to investigate the correlation of the two cytokines. To explore the molecular pathomechanism of the cytokine on brain injury caused by freshwater drowning and provide experimental evidence for developing a new pathway on clinical cytokine therapy.Methods1 seventy healthy Wistar rats were randomly divided into three groups: group Ⅰ (control group ) included 10 rats which did not be dealt with drowning;10 rats were assigned in groupII (drowning group ), they were drowned until death;group III (near drowning group ) included 50 rats that they were drowned for tow minutes. Each division of 10 rats were killed respectively at hour 3> 6^ 12> 24> 40 after they were taken out of the water. According to experimental requisition, the correlated index of the rats was detected.2 By the transcutaneous oxygen saturation meter, the dynamic saturation of blood oxygen was detected respectively at minute 0> 10n 30 and at hour K 3> 6> 12? 24> 40 after drowning, in order to observe hypoxic condition.3 To study morphology changes of the brain tissue, the brain paraffin sections of each group were stained with Hematoxylin Eosin (HE).4 The expression of HIF-1 a and VEGF at every phase of brain injury was detected by immunohistochemistry method. Results1 The interclass difference of brain index has statistic significance (P<0. 05). The brain index of group I (control group) was 6.87+0.78, the brain index of group II (drowning group) was higher than control group (P<0. 05). the brain index of the survivals at hour 3> 12 after drowning was smaller compared with group II (P<0. 05). But the numerical value of thebrain index between divisions at hour 24 and at hour 40 has no difference in statistics.2 The saturation of blood oxygen was 97 + 2 in the normal condition;The blood oxygen saturation was 52 + 5 ,which was instantly detected after drowning. The value gradually rose as time went by, and regained to normal degree at hour 12 after drowning. The interclass difference of blood oxygen saturation has statistic significance (P<0. 05).3 In aspect of brain histomorphology, brain cellular structure was clear without dropsy and bleeding in groupI (control group). In group II (drowning group), there were brain tissue looseness and wide diastem around small vessels and nerve cell, the volume of the part nerve cells increased, which was the appearance of cerebral edema. In group III (near drowning group ), the cerebral edema showed up at hour 3 after drowning and gradually aggravated from hour 12 to hour 24 after drowning. The worst appearance was at hour 24. The pathological changes of cerebral edema at hour 40 after drowning relieved lightly compared with that of hour 24, but it was accompanied with cellular necrosis^ degen and bleeding.4 About brain immunohistochemistry, the expression of HIF-a was negative, and the expression of VEGF showed lightlypositive (+) in group I (control group);both of their expression were positive (+) in group II (drowning group);in group III (near drowning group ), both of their expression were up-graded at hour 3 after drowning , and reached peak (+++) at hour 12. Subseqently their expression began to decrease. The interclass difference of HIF- a and VEGF was significant (P <0.05), and the expression of HIF-a was positive correlated with that of VEGF (P<0.05). Conclusion1 Hypoxic brain injury caused by freshwater drowning is a sort of serious pathological changes that closely relate with the progression and prognosis of the disease of drowning, but it is not the direct reason resulting in death.2 The high expression of hypoxia inducible factor - alpha (HIF-a ) is showed in the survival organism with drowning, and hypoxia inducible factor - alpha (HIF- a ) may increase the expression of vascular endothelial growth factor (VEGF) which situates its downstream gene domain. Tow kinds of cytokine play a protective role in brain injury. Nevertheless, with the improvement of organic hypoxia, their expression gradually decrease.3 In the course of treating drowning patient, the appropriatesupplement of exogenous HIF-a and VEGF may relieve the degree of brain injury, which is helpful to improve nervous symptom in clinical later period, and to cut down the incidence rate of sequela resulting from drowning in nervous system.