Effect and molecular mechanism of P13K/Akt signaling pathway on brain undergoing deep hypothermic low flow in mice

Objective To explore the effect and molecular mechanism of P13K/Akt signaling pathway on brain tissue of undergoing deep hypothermic low flow in mice.Methods The C57BL/6 mice (n =90) were randomly assigned into 3 groups:sham group,model group,and wortmannin group.Model group and wortmannin group were cerebral ischemia-reperfusion(I-R) group underwent deep hypothermic low flow and then reperfused and rewarmed,while the sham operation group excluded the arteries occlusion procedure.The protein expressions of akt,p-akt1 and p-gsk-3β were determined by Western blot and mRNA expressions of akt1,akt2 and akt3 were determined by real time RT-PCR at 2 h,24 h and 72 h after I/R respectively.Brain tissue was taken from five mice of each group at reperfusion 2h,24 h and 72 h timepoint respectively; then coronal slices were made and stained with 2,3,5-triphenyltetrazolium chlorid (TTC).The samples were postfixed and pictures were taken and analyzed.Results The deep hypothermic low flow had the characteristic changes of I/R injury.The protein expressions of p-akt1 and p-gsk-3β in model group were higher than those in other two subgroups at 24 h and 72 h after reperfusion(P＜0.05).The expressions of p-akt1 and p-gsk-3β were decreased at 24 and 72 hours after reperfusion in wortamnnin group (P＜0.05).The model group showed less pathological injury than wortmannin group at 24 h and 72 h after reperfusion(P＜0.05).There was no significant difference between akt1,akt2 and akt3 mRNA expressions at 2 h after reperfusion.The mRNA expressions of akt1 and akt2 were increased at 24 and 72 hours after reperfusion in model group than those in wortmannin and sham group (P＜ 0.05).No significant difference detected for akt2 mRNA expression between three groups.Conclusions These results suggest that that PI3K/Akt signaling pathway has cerebral protective effect in mice model undergoing deep hypothermia low flow by increasing the expression of p-akt1 and p-gsk-3β.The findings of real time PCR imply that akt1 mRNA and akt3 mRNA may play a role in the expression of p-akt1 and p-gsk-3β undergoing deep hypothermic low flow in mice. Key words: Brain ischemia;  Reperfusion injury;  Glycogen synthase kinase 3