Signaling pathway involved in hypoxia-inducible factor-1alpha regulation in hypoxic-ischemic cortical neurons in vitro.

Hypoxia-inducible factor-1alpha (HIF-1alpha) is a key transciptional regulator of cellular and systemic oxygen homeostasis. Previous studies have shown that the regulation of HIF-1alpha is involved in the activation of PI3K/Akt pathway in some cells. However, whether this pathway plays a role in modulating HIF-1alpha in cultured cortical neurons during hypoxia-ischemia (HI) remains unclear. We therefore investigated the relationship between phosphoinositid 3-kinase/Akt (PI3K/Akt) pathway and HIF-1alpha expression in cultured neurons using an oxygen and glucose deprivation (OGD) model. In this study, cortical neurons cultured in vitro were subjected to OGD for 3h followed by reperfusion. The expressions of HIF-1alpha, VEGF, total Akt and phosphorelated-Akt (p-Akt) were detected by RT-PCR, Western blot and immunocytochemistry. We found that HIF-1alpha and VEGF were increased at 4h and peaked at 8h after OGD. Meanwhile, p-Akt increased and peaked at 4h after reperfusion, preceding HIF-1alpha expression. Pretreatment with wortmannin, a PI3K/Akt pathway inhibitor, significantly inhibited p-Akt expression and further attenuated both transcription and translation of HIF-1alpha and VEGF. Collectively, our findings suggested that PI3K/Akt signaling pathway might be involved in HIF-1alpha regulation after OGD in cultured cortical neurons.