The aim of the present study was to examine the protective effects and mechanism of sika deer (Cervus nippon Temminck) velvet antler polypeptides (VAPs) against MPP+ exposure in the SH‑SY5Y human neuroblastoma cell line. MPP+ cytotoxicity and the protective effects of VAPs on the SH‑SY5Y cells were determined using an MTT assay. Cell apoptosis and mitochondrial membrane potential were detected using Hoechst 33342 and Rhodamine123 staining, respectively. Endoplasmic reticulum (ER) stress‑related reactive oxygen species (ROS) production in the SH‑SY5Y cells was detected using 2',7'‑dichlorodihydrofluorescein diacetate fluorescent probes. The expression levels of proteins, including caspase‑12, glucose regulated protein 78 (GRP78), CCAAT/enhancer binding protein homologous protein (CHOP) and phosphorylated c‑Jun N‑terminal kinase (p‑JNK) were detected using western blot analysis. The results showed that the half inhibitory concentration of MPP+ at 72 h was 120.9 µmol/l, and that 62.5, 125, and 250 µg/ml concentrations of VAPs protected the SH‑SY5Y cells under MPP+ exposure. When exposed to 120.9 µmol/l MPP+, changes in cell nucleus morphology, mitochondrial membrane potential and intracellular ROS were observed. VAPs at concentrations of 62.5, 125, 250 µg/ml reduced this damage. Western blot analysis showed that protein expression levels of caspase‑12, GRP78 and p‑JNK were upregulated in the SH‑SY5Y cells exposed to 120.9 µmol/l MPP+ for 72 h. In addition, 62.5, 125, and 250 µg/ml VAPs downregulated the expression levels of caspase‑12 and p‑JNK in a concentration‑ dependent manner, particularly the p‑JNK pathway. The effects of VAPs on GRP78 and CHOP were weak. In conclusion, MPP+‑induced SH‑SY5Y cell death may be linked to ER stress. VAPs prevented MPP+‑induced SH‑SY5Y cell death by affecting the p‑JNK pathway and caspase‑12‑mediated apoptosis. These findings assist in understanding the mechanism underlying the protective effect of VAPs on neurons.

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