Aim To investigate the protective effects of MANF on human neuroblastoma SH-SY5 Y cells suf-fering from oxygen-glucose deprivation/reperfusion ( OGD/R) and the underlying mechanism. Methods SH-SY5Y cells were treated with OGD for 6 h, fol-lowed by reperfusion for 12 h. Meanwhile, the cells were incubated with 2 μmol · L-1 recombinant human protein MANF for 12 h during reperfusion. The cell morphology was observed under an optical microscope. The cell viability was determined by MTT assay. PI
staining was performed to detect the number of dead cells. Western blot was performed to determine the protein levels of endogenous MANF, glucose-related protein 78 ( GRP78/BiP) , phosphorylated inositol re-quiring enzyme 1 ( p-IRE1 ) , phosphorylated eukaryot-ic translation initiator factor 2α ( p-eIF2α) , cleaved caspase-3, and C/EBP-homologous protein (CHOP). Results The cells exposed to OGD/R became smaller and round, and the neurites of the cells were shortened or disappeared . Recombinant human protein MANF
improved the survival rate ( P <0. 05 ) and decreased the death rate ( P <0. 05 ) of SH-SY5 Y cells treated with by OGD/R. Western blot assay showed that the endoplasmic reticulum ( ER) stress-associated proteins GRP78/BiP, p-IRE1, p-eIF2α, and MANF were in-creased significantly after OGD/R treatment, compared with the untreated controls. However, the increases of secretion levels of apoptosis-associated proteins CHOP
and cleaved caspase-3 in SH-SY5 Y cells induced by OGD/R were significantly suppressed by MANF. Con-clusion OGD/R up-regulates the ER stress-associated proteins and causes apoptosis. MANF inhibits OGD/R-induced cell death, which may be related to attenua-ting ER stress-induced apoptosis.