PCSK9 mRNA and protein levels were significantly increased following MCAO in hyperlipidemic mice. (A) mRNA and (B) protein levels of PCSK9 were significantly increased in HFD-fed mice subjected to MCAO, as demonstrated by reverse transcription-quantitative polymerase chain reaction and western blot analyses, respectively. (C) Representative western blotting image, displaying PCSK9 protein expression. (D) IHC analysis revealed that the gray value of PCSK9 was lower in the brain of HFD-MCAO mice compared with that in HFD-sham mice. (E) Representative images of IHC staining, showing PCSK9 protein expression. *P<0.05 and **P<0.01 vs. HFD-sham mice (n=4). PCSK9, proprotein convertase subtilisin/kexin type 9; MCAO, middle cerebral artery occlusion; HFD, high-fat diet; IHC, immunohistochemistry.