Protective Mechanism of Proprotein Convertase Subtilisin-Like Kexin Type 9 Inhibitor on Rats with Middle Cerebral Artery Occlusion-Induced Cerebral Ischemic Infarction

The aim of this study was to research the mechanism of proprotein convertase subtilisin-like kexin type 9 (PCSK9) inhibitor in neural protective effect on rat cerebral ischemic reperfusion injury (I/RI). The transient middle cerebral artery occlusion (tMCAO) model of rats was prepared by the suture method, and PCSK9 inhibitor was injected intraperitoneally immediately after I/R. The rats were scored for neurological deficits and the cerebral infarction volume was measured. The brain tissues were collected and western blot (WB) was used to detect the expression of PCSK9. The rat cortical neural stem cells were treated with oxygen glucose deprivation (OGD) to establish a cell model of ischemia/reperfusion. WB was used to detect the expression of PCSK9 and the apoptosis-related pathway proteins. After interfering with the expression of PCSK9 siRNA, the cell viability (cell counting kit-8 assay) and apoptosis (TUNEL staining, Annexin V/PI method) were detected, and the cell proliferation was detected by EdU staining and flow cytometry. The expression of PCSK9 in the brain tissue of the MCAO group was dramatically increased. PCSK9 inhibitor can improve neurobehavioral scores and reduce apoptosis and infarct volume. An OGD model of neural stem cells in vitro was constructed. Inhibiting PCSK9 with si-PCSK9 can increase cell viability, promote cell proliferation, and also reduce cell apoptosis. Inhibition of PCSK9 can decrease the cerebral infarct volume in rats with cerebral I/RI and improve the neural function. Mechanically, inhibition of PCSK9 can lead to the decrease of nerve cell apoptosis and promotion of cell proliferation.