Objective:To investigate the effect of brain derived neurotrophic factor on TrkB mRNA and Protein expression in embryonic rat brain suffered from intrauterine hypoxic-ischemic injury. Methods:The uterine arteries of pregnant rats were clamped for 30 min, and saline or BDNF was injected to the rat through caudal veins for 5 days. Rats with sham surgery were used as controls. The expression of TrkB mRNA and protein was measured using RT-PCR and Western blotting. Results:TrkB mRNA and levels of protein expression were higher in embryonic rat brain after clamping the uterine arteries of pregnant rats for 30 min than those in control group. BDNF injection could up-regulate the TrkB expression significantly. Conclusion:BDNF injection through rat caudal veins could up-regulate the levels of the TrkB mRNA and protein expression in embryonic rat brain suffered from intrauterine hypoxic-ischemic injury and may enhance its neuroprotection effect on cortical neurons.