Effects of mild hypothermia on expression of brain-derived neurotrophic factor mRNA in neonatal rats with hypoxic-ischemic brain damage

Objective To study the effect of mild hypothermia on brain-derived neurotrophic factor(BDNF)mRNA in neonatal rats with hypoxic-ischemic brain damage(HIBD).Methods Eight-four Wistar rats selected for this study that were 7 days old and weighed 13 to 16 g.The rats were randomly assigned into four groups,control group(n=6),sham operated group(n=6),HIBD group(n=36)and mild hypothermic group(n=36).The expression of BDNF mRNA of brain tissue was measured at 6、 12、 24、 48、 72 and 96 h by in situ hybridization.The apoptosis of neurons was measured by Tunel and HE kit.Results It was found that there was an increase of expression of BDNF mRNA in the dentate gyrus and hippocamapal CA1 area after hypoxic-ischemic injury in rats.It was significantly higher in level of BDNF mRNA of rats in mild hypothermic group than that in HIBD group.There was significant difference of apoptosis in neurons in gyrus and hippocamapal CA1 area of rats in mild hypothermia group compared with that in HIBD group.Conclusion Mild hypothermia can protect brain tissue by increasing the level of expression of BDNF mRNA and inhibiting apoptosis of neurons.