HIF-1Gene Expression Changes In Hypoxic-ischemic Brain Injury Rats Receiving Mild Hypothermia Interventionand Its Significance

Objective: Neonatal hypoxic ischemic encephalopathy (HIE) is a serious complicationafter neonatal asphyxia, illness weight can lead to permanent neurological disorders and evendeath, is one of the diseases of serious threat to neonatal health and life, at present there is lack ofeffective treatments for the disease clinically. In this study, the newborn rat model with hypoxicischemic brain damage (hypoxic-ischemic brain damage, HIBD) was established, mildhypothemia intervention was given for them, Brain specimens of each group were detected ateach time point for hypoxia-inducible factor-1α (Hypoxia-inducible factor-1α) content change.To discuss whether hypoxia-inducible factor–1α concentration changes can promote or inhibitcell apoptosis, and to offer new methods for HIE treatment to the majority of medical workers.Methods:120male or female SD rats which were7days old were selected, each one chosenbetween10-12g weight, and were randomly divided into low temperature group, control group,and mild hypothermia group, each group included40. In addition to the control of otherpreparation of hypoxic ischemic brain damage in rats in both groups, due to the need ofexperiments, according to the extraction of the brain at different time, the three groups were thenfurther divided into five groups, each group comprised of8:6hours,9hours,12hours,24hours,48hours groups. Ligation of left common carotid operation was made to moulds, after theligation, the newborn rats were put in92%of the nitrogen gas airtight glass storehouse for2h formaking animal model. The mild temperature intervention was immediately done after the modelswere successfully made. The rats in different groups were killed after dealed with hypoxicischemic brain damage for6hours,9hours,12hours,24hours,48hours respectively, then thebrain specimens were extracted. The differences of the morphology, hydroncus, shrink,liquefaction and necrosis between different brain tissue specimen groups were observed.Thereal-time fluorescence quantitative polymerase chain reaction (real-time PCR, RT-PCR) wasused to detect the expression of HIF-1α in brain tissue on the left side of the three groups of ratsat different time points. The datas were analyzed with associated statistic methods.Results: In sham group the expression of HIF-1α mRNAwas minimal and no significant changeamong all subgroups; in normothermia group the HIF-1α mRNA expression raised at6h andgradually increased,48h highest; in hypothermia group HIF-1mRNA began to increase at6h,and was inhibited at all time points compared with normothermia group (P <0.05).Conclusions:（1）the newborn rats to mild hypothermia after HIBD after intervention treatment can reduce the pathological changes of the brain tissue damage, prompt the low temperature ofnewborn rats HIBD has the nerve protective effect.(2) the hypoxic ischemic brain damage inneonatal rats enhanced HIF-1mRNAexpression, under hypothermia intervention HIF-1mRNAexpression is suppressed, antiapoptotic role, nerve cells of newborn rats hypoxia ischemia causeddamage to play a protective effect, for clinical provides the new ideas to treatment of neonatalhypoxic ischemic brain damage.