Abstract: Objective To investigate the role of abnormal methylation of the neuronal pentraxin 2(NPTX2)promoter region in cognitive impairment after acute cerebral infarction(ACI),and to analyze its relationship with the phosphatidylinositol 3-kinase/protein kinase B(PI3K/Akt)signaling pathway.Methods A rat model of middle cerebral artery occlusion/reperfusion(MCAO/R)was established using a modified suture method.Experimental animals were randomly divided into sham operation group,model group,demethylation intervention group,NPTX2 overexpression group,and NPTX2 overexpression+PI3K inhibitor group.Neurological function was assessed by modified neurological severity score(mNSS).Learning and memory abilities were evaluated by Morris water maze.Methylation status of the NPTX2 promoter region in hippocampal tissue was detected by methylation-specific PCR.The transcription and translation levels of NPTX2 were measured by qPCR and Western blotting,respectively.Neuronal apoptosis was analyzed by TUNEL staining.The phosphorylation level of key proteins of the PI3K/Akt pathway and the expression of apoptosis-related factors Bcl-2,Bax and Caspase-3 were detected by Western blotting.Results Compared with the sham operation group,rats in the model group showed significant cognitive decline and a marked increase in mNSS score.Meanwhile,the positive rate of NPTX2 promoter methylation in the hippocampus was significantly increased,NPTX2 mRNA and protein expressions were suppressed,the p-Akt/Akt ratio was decreased,and the number of apoptotic neurons was increased(all P<0.05).After different drug interventions,rats in the demethylation group and the NPTX2 overexpression group showed improved cognitive function,significantly decreased mNSS score,increased NPTX2 expression,increased p-Akt/Akt ratio,increased Bcl-2 protein expression,and decreased Bax and Caspase-3 protein expressions(all P<0.05).However,combined application of the PI3K inhibitor LY294002 significantly attenuated the neuroprotective effects induced by NPTX2 overexpression.Conclusion After acute cerebral infarction,hypermethylation of the NPTX2 gene promoter in the rat hippocampus leads to inhibition of its expression.This process may promote neuronal apoptosis by downregulation of the PI3K/Akt signaling pathway,thereby exacerbating the progression of cognitive dysfunction.

Key words: acute cerebral infarction, cognitive dysfunction, NPTX2, DNA methylation, PI3K/Akt signaling pathway, neuronal apoptosis