Morroniside protects HT-22 cells against oxygen-glucose deprivation/reperfusion through activating the Nrf2/HO-1 signaling pathway

Neonatal hypoxic-ischemic encephalopathy (HIE) is a devastating condition that affects neurodevelopment and results in brain injury in infants. Morroniside (MOR), a natural secoiridoid glycoside, has been found to possess neuroprotective effect. However, the effects of MOR on neonatal HIE are unclear. An <i>in vitro</i> HIE model was established in murine hippocampal neurons HT-22 cells using oxygen-glucose deprivation/reoxygenation (OGD/R) stimulation. Our results showed that MOR improved OGD/R-caused cell viability reduction in HT-22 cells. MOR suppressed the production of reactive oxygen species (ROS) and malondialdehyde (MDA) in OGD/R-induced HT-22 cells in a dose-dependent manner. The activities of superoxide dismutase (SOD) and glutathione peroxidase (GP_X) were significantly elevated by MOR. Moreover, MOR treatment caused a significant increase in bcl-2 expression, and obvious decreases in the expression levels of bax, cleaved caspase-3, and cleaved caspase-9 expression. Furthermore, MOR significantly upregulated the expression levels of nuclear Nrf2 and HO-1 in OGD/R-treated HT-22 cells. Additionally, knockdown of Nrf2 or HO-1 abrogated the effects of MOR on OGD/R-induced oxidative stress and apoptosis in HT-22 cells. In conclusion, these findings suggested that MOR protects HT-22 cells against OGD/R <i>via</i> regulating the Nrf2/HO-1 signaling pathway.