Objective: To investigate the changes of TrkB and Ras-MAPK in brain-derived neurotrophic factor (BDNF) protecting the embryonic rat cerebral cortical neurons against hypoxia-induced neurotoxicity.
Methods: The immunofluorescence technique, laser scanning confocal microscope and half-quantitative analysis were done to explore the changes of the intracellular levels of tyrosine kinase B (TrkB), phosphorylated TrkB and the mitogen-activated protein kinase (MAPK) in rat embryonic cortical neurons cultured in different time groups of hypoxia with or without BDNF pretreatment.
Results: The fluorescent intensity of TrkB and phosphorylated TrkB in the cytoplasm and the fluorescent intensity of MAPK in both cytoplasm and cell nucleus of the neurons were significantly increased in the presence of BDNF (P < 0.05), the fluorescent intensity of neurons pretreated with BDNF 24 h before the hypoxia culture was stronger than those with BDNF just before the hypoxia culture (P < 0.05).
Conclusion: The Ras-MAPK approach may be the major signal transferring way of BDNF in protecting the cortical neurons from hypoxia-induced neurotoxicity. The approach of signal transferring begins with tyrosine phosphorylation of TrkB receptors.