Neuroprotection of brain-derived neurotrophic factor against hypoxic injury in vitro requires activation of extracellular signal-regulated kinase and phosphatidylinositol 3-kinase.

Intrauterine asphyxia is one of the major contributors for perinatal death, mental and physical disorders of surviving children. Brain-derived neurotrophic factor (BDNF) provides a promising solution to hypoxic injury due to its survival-promoting effects. In an attempt to identify possible molecular mechanisms underlying the neuroprotective role of BDNF, we studied extracellular signal-regulated kinase (ERK), phosphatidylinositol 3-kinase (PI-3-K) and p38 mitogen-activated protein kinase (MAPK) pathways. We demonstrated that BDNF protected cortical neurons against hypoxic injury in vitro via activation of both the ERK and PI-3-K pathways but not the p38 MAPK pathway. We also showed that both hypoxic stimuli and exogenous BDNF treatment phosphorylated the cyclic AMP response element-binding protein (CREB) and that CREB phosphorylation induced by BDNF was mediated via the ERK pathway in cultured cortical neurons.