Objective

Mitochondrial dysfunction is the key factor in rotenone-induced neurotoxicity in dopaminergic neurons. This study aimed to investigate the role and potential mechanism of the mitochondrial DNA encoded peptide Humanin (HN) in alleviating rotenone-induced neurotoxicity.

Methods

Rotenone was added to the cultured PC12 cells to induce neurotoxicity. PC12 cells were preincubated with HN, which has a protective effect. Cell counting kit-8 (CCK-8) was used to evaluate PC12 cell viability. Flow cytometry to detect the content of reactive oxygen species (ROS) in PC12 cells. Western blot analysis was used to detect the expression of superoxide dismutase 2 (SOD2), acetylated SOD (Ac-SOD), sirtuin 3 (SIRT3), nuclear factor erythroid 2-related factor 2 (Nrf2), heme-oxygenase-1 (HO-1), and NAD(P)H:quinone oxidoreductase 1 (NQO1). The corresponding kits were used to measure the NAD+/NADH ratio and SOD content separately.

Results

HN pretreatment significantly increased PC12 cell survival, reduced ROS formation, and increased the NAD⁺/NADH ratio. It also increased the expression of SIRT3, Nrf2, HO-1, and NQO1 proteins and decreased the expression of Ac-SOD protein under rotenone exposure. At the same time, it also activated the Nrf2/HO-1 signaling pathway, which depends on HN-mediated SIRT3 activation.

Conclusion

These results suggest that HN plays a protective role in rotenone-induced neurotoxicity by suppressing oxidative stress and activating the antioxidant response via the Nrf2/HO-1 pathway, which is regulated by SIRT3 in PC12 cells.