Role of TLR4/Src signaling pathway in activation of NLRP3 inflammasomes in hippocampus in a rat model of hepatic ischemia-reperfusion / 中华麻醉学杂志

ABSTRACT

Objective:To evaluate the role of Toll-like receptor 4(TLR4)/Src signaling pathway in activation of nucleotide-binding oligomerization domain-like receptor containing pyrin domain 3 (NLRP3) inflammasomes in hippocampus in a rat model of hepatic ischemia-reperfusion (I/R).Methods:Thirty-two clean-grade healthy Sprague-Dawley rats, aged 8 weeks, weighing 200 g, were divided into 4 groups ( n=8 each) using a random number table method: sham operation group (Sham group), hepatic I/R group (HIR group), Toll-like receptor 4 (TLR4) inhibitor TAK-242 treatment group (TAK-242 group), and Src inhibitor PP2 treatment group (PP2 group). Hepatic I/R model was established by clamping hepatic vessels for 1.5 h followed by reperfusion in anesthetized rats.TAK-242 0.5 mg/kg was injected via the tail vein at 30 min before establishing the model in group TAK-242.PP2 0.03 mg/kg was intraperitoneally injected for 3 consecutive days before establishing the model in group PP2.The animals were sacrificed at 6 h of reperfusion, and hippocampal tissues were extracted for determination of interleukin-1β (IL-1β) and interleukin-18 (IL-18) contents (by enzyme-linked immunosorbent assay), malondialdehyde (MDA) content (by TBA method), superoxide dismutase (SOD) activity (using total superoxide dismutase assay), and expression of NLRP3, apoptosis-associated speck-like protein containing CARD (ASC), c-Src, pro caspase-1, cleaved caspase-1, TLR4 and phosphorylated Src (p-Src) (Western blot). Results:Compared with Sham group, the contents of IL-1β, IL-18 and MDA were significantly increased, the SOD activity was decreased, and the expression of NLRP3, cleaved caspase-1, ASC, TLR4 and p-Src was up-regulated in the other three groups ( P<0.05). Compared with HIR group, the contents of IL-1β, IL-18 and MDA were significantly decreased, the SOD activity was increased, and the expression of NLRP3, cleaved caspase-1, ASC, TLR4 and p-Src was down-regulated in TAK-242 group and PP2 group ( P<0.05). There was no significant difference in each index between TAK-242 group and PP2 group ( P>0.05). Conclusion:The mechanism underlying activation of NLRP3 inflammasomes in hippocampus is related to activating TLR4/Src signaling pathway in a rat model of hepatic I/R.