This study aims to explore the impact of β-nicotinamide mononucleotide(NMN) on oxygen glucose deprivation(OGD)-induced autophagy in PC12 cells and its potential mechanisms.An in vitro model of OGD-induced autophagic injury in PC12 cells was established,and cell viability in each group was measured using the MTT assay.The autophagosomes and autolysosomes after NMN treatment were observed by transmission electron microscopy,and the effect of NMN on autophagosomes was observed by MDC fluorescence staining.Western blot analysis was conducted to evaluate the expression levels of autophagy-related proteins,including LC3-II/LC3-I,Beclin1,p62,P-mTOR/mTOR,and others.The results showed that compared with control group,the survival rate of OGD group was significantly decreased (P<0.01),the number of autophagosomes and autolysosomes increased (P<0.01),and the fluorescence spots and intensity of MDC were enhanced (P<0.01).The expressions of Beclin1 and LC3-II/LC3-I were significantly up-regulated (P<0.01),while the expressions of p62 and P-mTOR /mTOR were significantly down-regulated (P<0.01).Compared to the OGD group,the survival rate of NMN group was significantly increased (P<0.01),the autophagosome and autolysomes were decreased in the NMN and 3-methyladenine(3-MA) group (P<0.01),and the fluorescence spots and intensity of MDC were decreased (P<0.01).the expressions of Beclin1 and LC3-II/LC3-I were down-regulated (P<0.01),and the expressions of p62 and P-mTOR /mTOR were up-regulated (P<0.01),but the opposite was true in RAPA group.Compared with rapamycin(RAPA) group,the autophagosomes and autolysosomes in RAPA+NMN group were significantly decreased (P<0.01),the fluorescence spots and intensity of MDC were decreased (P<0.01),and the expressions of Beclin1 and LC3-II/LC3-I were significantly down-regulated (P<0.01).The expressions of p62 and P-mTOR /mTOR were significantly up-regulated (P<0.01).Therefore,NMN can inhibit OGD-induced autophagy injury in PC12 cells and play a protective role against neuronal autophagy injury,and this protective effect may be related to mTOR pathways.This study can provide a certain target reference for NMN prevention and treatment of OGD-induced autophagy injury,and accumulate some laboratory data for the development of natural compounds.