Role of P2X7/NLRP3 inflammasome pathway in cognitive impairment in sleep deprived mice / 中华行为医学与脑科学杂志

ABSTRACT

Objective:To investigate the possible role and mechanism of purinergic ligand-gated ion channel 7(P2X7)/nucleotide-binding oligomerization domain-like receptor protein 3(NLRP3) inflammasome pathway in cognitive impairment induced by sleep deprivation (SD)mice.Methods:SPF grade male C57BL / 6J mice aged 6-8 weeks were randomly divided into 3 groups according to the random number table method with 6 mice in each group.They were normal control group (CC group), SD group and SD+ P2X7 receptor antagonist brilliant blue G(BBG) group (SD+ BBG group). Modified multiple platform method was used to establish a 5-day SD model in mice.During the SD intervention period, the mice in SD+ BBG group were injected with BBG(50 mg/kg) intraperitoneally once a day, while the mice in CC group and SD group were injected with the same volume of 0.9% sodium chloride solution.Morris water maze was conducted to evaluate the cognitive function of mice.The protein expression levels of P2X7, NLRP3, caspase-1, apoptosis-associated proteins(ASC) and interleukin-1β(IL-1β) in hippocampus were detected by Western blot.RT-qPCR was used to detect the mRNA expression levels of tumor necrosis factor-α(TNF-α), IL-1β, interleukin-18(IL-18) and microglial polarization surface markers CD206 and CD86 in hippocampus.Graph pad Prism 8.0 software and SPSS 25.0 software were used for statistical analysis and mapping.Results:(1) The interaction effect between time and groups of escape latency in three groups of mice was significant ( F=15.76, P<0.001). From the 2nd to 5th day, the escape latencies of mice in SD group were higher than those of CC group, while the escape latencies of mice in SD+ BBG group were lower than those of SD group (all P<0.05). (2)The results of the space exploration experiment showed that there were statistically significant differences in target quadrant residence time and the times of crossing the platform( F=6.65, P=0.009; F=12.39, P<0.001). The target quadrant residence time ((23.42±0.55) s) and times of crossing the platform ((17.67±0.71) times) of the SD group were both lower than those of the CC group ((29.48±1.78) s, (23.33±0.95) times) (both P<0.05), while the target quadrant residence time ((28.62±1.19) s) and the times of crossing the platforms ((21.33±0.76) times) of the SD+ BBG group were both higher than those of the SD group (both P<0.05). (3)There were statistically significant differences in the protein levels of inflammatory related proteins such as P2X7, NLRP3, caspase-1, ASC and IL-1β in the hippocampus of mice among the 3 groups( F=8.23, 8.97, 8.45, 54.42, 8.12, all P<0.05). Compared with CC group, the protein levels of P2X7 ((0.93±0.02), (0.71±0.04)), NLRP3 ((0.97±0.04), (0.62±0.09)), caspase-1 ((1.00±0.03), (0.76±0.07)), ASC ((0.96±0.02), (0.77±0.04)) and IL-1β ((0.85±0.07), (0.54±0.04)) in SD group were all higher (all P<0.05). Compared with SD group, the protein levels of P2X7 (0.74±0.05), NLRP3 (0.78±0.02), caspase-1 (0.74±0.04), ASC (0.67±0.02), IL-1β (0.53±0.07) in SD+ BBG group were all lower (all P<0.05). (4)There were statistically significant differences in the mRNA levels of IL-18, IL-1β, TNF-α, CD86 and CD206 in hippocampus among the three groups ( F=12.80, 12.28, 105.80, 7.06, 30.19, all P<0.05). The mRNA levels of IL-18, IL-1β, TNF-α, CD86 in SD group were all higher than those in CC group(all P<0.05), while the mRNA level of CD206 in SD group was lower than that in CC group( P<0.05). Compared with SD group, the mRNA levels of IL-18, IL-1β, TNF-α, CD86 were lower in SD+ BBG group (all P<0.05), while the CD206 mRNA level of SD+ BBG group was higher than that in SD group( P<0.05). Conclusion:SD intervention can lead to cognitive impairment and increased expression of P2X7 in hippocampus of mice, which may be related to the activation of P2X7/ NLRP3 inflammasome signaling pathway, promoting the polarization of microglia into pro-inflammatory type and up-regulating the expression of pro-inflammatory cytokines.Inhibition of P2X7 can improve the cognitive function of mice.