The Role Of TLR4/NF-κB Signaling Pathway In Rats Long-term Cognitive Dysfunction Induced By Sevoflurane Exposure During Neonatal Period

Objective: To investigate the effects of sevoflurane early and multiple exposure on TLR4/NF-κB,Tumor necrosis factor α(TNF-α)and interleukin-6(IL-6)in hippocampus of rats.To investigate the relationship between TLR4/NF-κB pathway and long-term cognitive changes induced by repeated sevoflurane exposure.Methods :(1)15 P7 D rats,5 in each group,were divided into C group,S group and T group.Group S and T were exposed to 3% sevoflurane for 2h,group T was intraperitoneally injected TAK242(TLR4 specific inhibitor)1h before exposure,and group C was blank control.Rats were examined by blood gas analysis of after exposure.(2)30 P7 D rats,15 in each group,were divided into group C and group S.Group S was exposed to 3% sevoflurane for 2h for 3 consecutive days,and group C was blank control.The expression of TLR4 in hippocampus of 5 rats in each group was measured by western blotting at 12,24 and 36 hours after exposure.(3)63 P7 D rats were divided into C group,S group and T group,with 21 rats in each group.Group S and GROUP T were exposed to 3% sevoflurane for 2h for 3 consecutive days.Group T was intraperitoneal injected TAK242 1h before exposure,while group C was not treated.The expression of TLR4/NF-κB in hippocampus of 13 rats in each group was observed by western blotting and immunofluorescence,and il-6 and TNF-α in hippocampus were measured by enzyme linked immunosorbent assay(elisa)24h after exposure.(4)The remaining 8rats in each group were evaluated by Morris water maze at 8 weeks of age.Results :(1)there were no hypoxia,carbon dioxide retention and p H abnormality in the three groups.(2)Compared with group C,the expression of TLR4 in hippocampus of group S increased at 12,24 and36 hours after sevoflurane exposure(P < 0.05),and the increase was the largest at 24 hours after sevoflurane exposure.(3)Compared with group C,the expression of TLR4 and phosphorylated NF-κB P65 in hippocampus of groups S and T were increased(P < 0.05);Compared with group S,the expression of TLR4 and phosphorylated NF-κB P65 in hippocampus of rats in group T decreased(P < 0.05).Compared with group C,il-6 and TNF-α in hippocampus of group S and T were increased(P < 0.05),while il-6 and TNF-α in hippocampus of group T were decreased compared with group S(P < 0.05).(4)Compared with group C,the escape latency of group S was prolonged from the second day to the fifth day(P < 0.05);Compared with group S,the escape latency of group T,on the second and third day was shortened(P <0.05).Compared with group C,the time spent in the target quadrant and the crossing times of the original platform in group S were decreased,and the first crossing time of the platform was prolonged(P <0.05).Compared with group S,the time of the rats crossing the platform for the first time in group T was shortened and the time spent on target quadrant was prolonged(P < 0.05),but there was no statistical difference in the times of rats crossing the original platform(P>0.05).Conclusions: For P7 D rats,exposure to 3% sevoflurane for 2 h for 3consecutive days led to long-term changes in cognitive function,that was associated with activation of the hippocampus TLR4/NF-κB signaling pathway and increased proinflammatory factors.