Effect Of PI3K/Akt Signaling Pathway On The Function And TNFR Expression Of Microglia

Objectives: To explore the underlying mechanisms modulating the function ofmicroglia by investigating the effects of PI3K/Akt signaling pathway on the function ofmicroglia and the expression of TNFR.Methods: BV2cell and PC12cell lines were used to stand for microglia andneurons respectively in this study. PC12cell was cultured with the supernatant of BV2cell, and the function of BV2cell was evaluated by measuring the survival rate of PC12cell with the method of MTT. In order to make clear the influence of PI3K/Aktsignaling pathway on the function of microglia, PC12cell was divided as normal,hydrogen peroxide injury, hypoxia and PI3K/Akt inhibitor groups. To specify the effectof PI3K/Akt signaling pathway on the expression of TNFR under different functions ofmicroglia, BV2cell was divided as normal, hypoxia and PI3K/Akt inhibitor groups.Western blotting was used to detect the levels of Akt phosphorylation and TNFR.Results:1. The survival rate of PC12cell was supposed as100%in normal group. That ofPC12cell in the hydrogen peroxide injury group was51.13±1.24%. And the survivalrate of PC12cell at1.5h,4h,8h and14h were78.41±2.23%，51.60±0.51%，33.63±1.02%and23.62±2.91%respectively in hypoxic groups. Comparing with the hydrogenperoxide injury group, the survival rate was significantly increased at1.5h anddecreased obviously at8h and14h（P＜0.05）.The survival rate of PC12cell declined to55.24±0.98%，34.91±0.67%，21.44±1.73%and11.02±1.76%respectively whenPI3K/Akt signaling pathway inhibitor was used（P＜0.05）. 2. In normal group, the level of p-Akt in BV2cells was65.94±1.66. The levels ofp-Akt were74.15±2.69,68.45±1.68,45.66±2.36and42.81±1.05respectively when theBV2cell was cultured under hypoxia for1.5h,4h,8h and14h. Compared with normalgroup, the level of p-Akt increased significantly at1.5h, but gradually decreased at8hand14h (p<0.05).3. There were the expression of TNFR1and TNFR2on the BV2cells in normoxia.The levels of TNFR1and TNFR2were6.54±0.18and15.27±0.13in normal group.The expression levels of TNFR1and TNFR2respectively increased to8.01±0.13，19.92±0.64when BV2cell was cultured in hypoxia for1.5h. The levels of TNFR1markedly increased to8.87±0.57，16.33±0.98and17.84±0.53when BV2cell wascultured in hypoxia for4h,8h and14h respectively (all p<0.05). The levels of TNFR2gradually decreased to15.58±0.83,12.79±0.47and10.32±0.93prolonging the length ofhypoxia culture to4h,8h and14h respectively. Compared with normal group, the levelsof TNFR2at8h and14h in the hypoxia group was significantly decreased(p<0.05).After adding the PI3K/Akt signaling pathway inhibitor, the levels of TNFR2decreased respectively to15.86±0.54，11.83±0.74，6.87±0.47and6.01±0.53whenBV2cell was cultured in hypoxic for1.5h,4h,8h and14h. The levels of TNFR1were7.79±0.57,9.27±0.76,17.87±1.29and17.78±0.73respectively when BV2cell wascultured in hypoxic for1.5h,4h,8h and14h. The differences in the levels of TNFR2between the hypoxia and PI3K/Akt inhibitor groups was significantly (all p<0.05).However, the differences of the levels of TNFR1had no statistical significance betweenthe hypoxia group and PI3K/Akt inhibitor group.Conclusions:TNFR2might transmit information mainly by PI3K/Akt signaling pathway andmediate the neuroprotective effect of microglia.