Role of TLR4-p38MAPK-NF-κB signaling pathway in sevoflurane-induced decrease in cognitive function of aged rats / 中华麻醉学杂志

ABSTRACT

Objective To evaluate the role of Toll-like receptor 4 (TLR4)-p38 mitogen-assoliated protein kinase (p38MAPK)-nuclear factor kappa B (NF-κB) signaling pathway in sevoflurane-induced decrease in cognitive function of aged rats.Methods Sixty SPF healthy male Sprague-Dawley rats,aged 20 months,weighing 550-750 g,were divided into 5 groups (n =12 each) using a random number table method:control group (C group),sevoflurane group (S group),TAK242 plus sevoflurane group (TS group),SB202190 plus sevoflurane group (SS group),and PDTC plus sevoflurane group (PS group).All the rats were intubated after anesthesia and connected to an animal ventilator.TAK242,SB202190 and PDTC 10 μl were injected into the lateral cerebral ventricle in TS,SS and PS groups,respectively,and normal saline containing the equal volume of DMSO was given in C and S groups.Starting from 10 min after lateral cerebral ventricle injection,4％ sevoflurane was inhaled for 6 h via the tracheal tube,with the inhaled oxygen concentration 30％ and oxygen flow rate 2 L/min.The mixture of air and oxygen was inhaled in C group.The learning and memory ability was assessed by Morris water maze test at 7 days after the end of sevoflurane anesthesia,and the escape latency and swimming distance were recorded.Animals were sacrificed after the end of Morris water maze test,and brains were removed and hippocampi were isolated for determination of neural apoptosis (by TUNEL),contents of tumor necrosis factor-alpha (TNF-α) and interleukin-1beta (IL-1β) in hippocampal tissues (by enzyme-linked immunosorbent assay),and expression of caspase-3,phosphorylated p38MAPK (p-p38MAPK),total p38MAPK (t-p38MAPK) and NF-κB in nucleus (by Western blot).The apoptosis rate and p-p38MAPK/t-p38MAPK ratio were calculated.Results Compared with C group,the escape latency and swimming distance were significantly prolonged at each time point,the apoptosis rate and contents of TNF-oα and IL-1β were increased,the expression of caspase-3,p-p38MAPK and NF-κB was up-regulated,and p-p38MAPK/t-p38MAPK ratio was increased in the other four groups (P＜0.05).Compared with S group,the escape latency and swimming distance were significantly shortened at each time point,the apoptosis rate and contents of TNF-α and IL-1β were decreased,and the expression of caspase-3 was down-regulated in TS,SS and PS groups,the expression of NF-κB was significantly down-regulated in TS and SS groups,and the expression of p-p38MAPK was significantly down-regulated,and p-p38MAPK/t-p38MAPK ratio was decreased in TS group (P＜0.05).Compared with TS group,the escape latency and swimming distance were significantly prolonged at each time point,the apoptosis rate and contents of TNF-α and IL-1β were increased,the expression of caspase-3 and p-p38MAPK was up-regulated,and p-p38MAPK/t-p38MAPK ratio was increased in SS and PS groups,and the expression of NF-κB was significantly up-regulated in PS group (P＜0.05).The expression of NF-κB was significantly up-regulated in PS group when compared with SS group (P＜0.05).Conclusion TLR4-p38MAPKNF-κB signaling pathway is involved in sevoflurane-induced decrease in cognitive function of aged rats.