Effects Of Noruiothermic Cardiopulmonary Bypass On C-fos Gene Expression In Hippocampi Of Rats

Objective：To investigate the effects of normothermic cardiopulmonary bypas（sCPB）on c-fos gene expression in hippocampol of rats，establishing a rat model of CPB.Methods:Twelve adult male Sprague-Dawley（SD）rats were randomly divided intoSham group（n=6）,and CPB group（n=6）.All animals were anesthetized（350mg·kg-1of chloraldurat for intraperitoneal）,orally intubated and mechanically ventilated.Theright atrium was cannulated via the right superior vena and right internal carotid arterywas cannulated.The systemic anticoagulation was achieved with heparin(500U·kg-1).The animals seleted for CPB group underwent normothmic(above36℃) CPB at a flow of（120～150）ml·kg-1·min-1for60minutes,with the blooddrained from the right caveatrium and infused into the right internal carotidartery.Sham group underwent all the same operations except for CPB.During theprocedures,body temperature(T) and MAP were monitored,while arterial bloodgas,electrolytes and hemodilution parameters were analyzed.1hour after CPB in CPBgroup,2hours after operation in Sham group, the animals were killed and hippocampiwere removed,the left hippocampi preserved in nitrogen canister for the detection ofc-fos mRNA,while the right ones preserved in4%polymerized formaldthyde for theexamination with immunohistochemical technique.Hippocampal c-fos mRNAexpressions were determined with reverse transcriptase polymerase chainreaction(RT-PCR)method.Results:1. All animals survived during the whole process.There were no significantdifference in weight and blood gas analysis index between both group at every timepoint observed(p>0.05).Electrolytes(K+、Ca2+),hematocrit (Hct) and haemoglobinlevels (Hb) of CPB group changed significantly comparing to those of Sham group (P ＜0.05),showing that K+、Ca2+、Hct and Hb decreased.2. Hematoxylin-eosin staining（HE） showed that hippocampal neurons of Sham group were nearlynormal,pyramidal cells oval, clear nucleolus, and no obvious pathological changes；Hippocampal neurons of CPB group were swollen, nuclear condensation and (or)nuclear fragmentation and atrophy.3.Hippocampal slices by immunohistochemicalstaining showed that the expression of c-fos at a low levels and the positive cellstaining lighter in sham group.The c-fos of CPB group expressed at high levels,stained dark,the structure of the neurons is clear and complete, and the positivematerial located within the nucleus.4.In the electropherogran of RT-PCR product, theelectrophoresis strips of CPB group were brighter and clearer than those of Shamgroup.The calculation of gelatum image analytical system showed that thec-fos/β-actin ratio in CPB group was siganificantly higher than that in Sham group (P＜0.05), suggesting that hippocampal c-fos mRNA expressions in CPB group washigher than that in Sham groupConclusions:1.Normothermic CPB can induce injury to hippocampus inrats.2.Normothermic CPB can induce hippocampal c-fos mRNA expressions inrats.3.Normothermic CPB can induce hippocampal c-fos mRNA expressions inrats.4.C-fos can use as a indicator of CPB resulting brain damage in early diagnosis.