17-DMAG Protects Against Hypoxia-/Reoxygenation-Induced Cell Injury in HT22 Cells Through Akt/Nrf2/HO-1 Pathway

Oxidative stress is well known to play a pivotal role in hypoxia/reoxygenation (H/R)-induced neuron injury. On the basis of this fact, antioxidative agents have been demonstrated to be neuroprotective. 17-DMAG (HSP90 inhibitor) is reported to have neuroprotective effects in vitro, which may interfere with oxidative stress through reduction in pro-oxidative factors. However, little is known about its effects on H/R-induced neuron injury and the underlying mechanisms. In this study, the effects of 17-DMAG on H/R-treated HT22 cells were investigated. MTT and lactate dehydrogenase (LDH) assays indicated that 17-DMAG led to a dose-dependent recovery of cell viability in H/R-treated HT22 cells. Flow cytometry demonstrated that 17-DMAG inhibited the cell apoptosis induced by H/R in HT22 cells. In addition, Western blot and real-time reverse transcription-polymerase chain reaction indicated that 17-DMAG inhibited the H/R-induced upregulation of Bax/Bcl-2 ratio and cleaved caspase-3 expression. Moreover, our results demonstrated that 17-DMAG promoted the expression of antioxidant enzymes, including manganese superoxide dismutase, catalase, and glutathione peroxidase. As a result, 17-DMAG might resist to H/R-induced oxidative stress. Furthermore, 17-DMAG increased the expression of phosphorylation of Akt (p-Akt) and the heme oxygenase-1 (HO-1), as well as the translocation of nuclear factor erythroid 2-related factor 2 (Nrf2) in H/R-treated HT22 cells. However, the Akt inhibitor, LY294002, partially hampered the effects of 17-DMAG on the expression of p-Akt, nuclear Nrf2, and HO-1 and cell viability, as well as cell apoptosis induced by H/R in HT22 cells. In conclusion, the findings of our study thus demonstrate that 17-DMAG protects against H/R-induced HT22 cell injury through Akt/Nrf2/HO-1 pathway, which may be associated with its antiapoptotic and antioxidative stress effects.