Can Na+/K+ATPase be a novel target to treat anxiety?A hint from its regulatory effect on neuroinflammation

摘要

OBJECTIVE Na+/K+-ATPase(NKA)is large membrane protein expressed uni⁃versally which is indispensable for the mainte⁃nance of ionic gradient as well as neuronal excit⁃ability.The role of NKA in inflammatory regula⁃tion is still unclear.Inflammatory responses are initiated upon the activation of inflammasomes.In order to investigate the crosslink between NKA and inflammasome,NKAα1 knockout(KO)N2a cells were generated using CRISPR/Cas9 system.METHODS AND RESULTS qPCR results showed that NLRP1 and NLRP3 were upregulated in response to NKAα1 loss while both NLRC4 and AIM2 remained unaffected.Meanwhile,consistent with the change in NLRP1 and NLRP3,both the mRNA level of ASC and IL-1βwere significantly increased in NKAα1 KO cells.These data indicated that NKAα1 interfer⁃ence might influence the level of NLRP1 and NLRP3 inflammasomes in neuronal cells.Further evidence indicating the potential link between NKA and inflammasome pathway were provided using cytokine array assay where all the differen⁃tiated protein detected were closely linked to NLRP1 and NLRP3.To confirm this effect,we also observed the transcriptional levels of inflam⁃masome proteins in the brain cortex from both NKAα1+/+and NKAα1+/-mice.In line with the observation gained in NKAα1 KO cells,the mRNA level of NLRP1,NLRP3 and IL-1βwere significantly upregulated in NKAα1+/-mice brain.Interestingly,in the primary cultured astrocytes,treatment with LPS/ATP significantly reduced the mRNA and protein levels of NKAα1 expression.These data imply that a negative regulation loop between NKAα1 and inflammation may exist in the central nervous system.Since neuroinflam⁃matory mechanism is currently considered the most potential of interventions to target anxiety,we therefore perform behavioural experiments to investigate the role of NKAα1 in anxiety.Chronic restraint stress(CRS)for 10 d significantly reduced the time and frequency of entering the open arm and prolonged the retention time in the closed arm in the elevated plus-maze test.In the open field test,CRS also reduced both duration and frequency of entering into the central region.Although NKAα1 loss itself did not alter the behaviour performance in the normal condition,it exacerbated CRS-induced above behaviour abnormalities.CONCLUSION NKAα1 is regulat⁃ed upon inflammatory challenger and may be a novel target to treat anxiety.