HIF-α/PKM2 and PI3K-AKT pathways involved in the protection by dexmedetomidine against isoflurane or bupivacaine-induced apoptosis in hippocampal neuronal HT22 cells

The present study investigated the mechanism underlying the protective effect of dexmedetomidine (Dex) on hippocampal neuronal HT22 cell apoptosis induced by the anesthetics isoflurane and bupivacaine. The cellular morphology was observed using a phase contrast microscope. The effects of anesthetics on cell proliferation were assayed using a Cell Counting Kit-8 (CCK-8). The levels of apoptosis were examined by flow cytometry utilizing Annexin V-fluorescein isothiocyanate/propidium iodide double staining, and the protein expression levels of cleaved caspase-3, phosphorylated phosphoinositide 3′-kinase (p-PI3K), p-protein kinase B (p-AKT), hypoxia inducible factor (HIF-α), pyruvate kinase M2 (PKM2), B-cell lymphoma (Bcl-2)-associated X protein (Bax), Bcl-2 and cytochrome c were detected by western blot analysis. In vitro treatment with anesthetics was identified to decrease cell proliferation (P<0.01), the effect of which was then markedly inhibited by treatment with Dex (P<0.01) or a PI3K/AKT agonist. Exposure to anesthetics induced apoptosis in HT22 cells (75.4%), which was significantly attenuated by co-treatment with Dex (26.2%) or the PI3K/AKT agonist (28.1%). Analysis of the protein expression levels revealed that exposure to anesthetics resulted in the activation of cleaved caspase-3, Bax, cytochrome c, HIF-α and PKM2 and decreased the expression levels of Bcl-2, p-PI3K and p-AKT. However, these changes were inhibited by treatment with Dex or the PI3K/AKT agonist. Dex protected hippocampal neuronal HT22 cells from anesthetic-induced apoptosis through the promotion of the PI3K/AKT pathway and inhibition of the HIF-α/PKM2 axis.