The Role Of Trka/Trkb In Radiation-Induced Hippocampal Neurogenesis Impairment

Objective To investigate the roles of TrkA and TrkB in radiation-induced hippocampal neurogenesis impairment.Methods Fifty-six rats were randomized into radiation group and sham control group.Radiation group received whole brain irradiation at a single dose of 10 Gy.The hippocampus were separated from rats in day 1,day 3,day 14 and 1 month after irradiation.Western blot and RT-PCR were applied to detect the protein levels and mRNA levels.Golgi staining was used to observe the dendritic spine of hippocampus.Immunofluorescence was performed to detect neural precursor's proliferation.Results Compared with control group,the numbers of dendritic spine significantly decreased after irradiation and its shape change obviously.Immunofluorescence showed a significant decrease in neural precursor's proliferation comparing with control group (t =6.49,P ＜ 0.05).Protein level of TrkA expression increased (t =2.64,3.06,4.80,2.64,P ＜ 0.05),while the levels of TrkB protein expression decreased significantly (t =4.59,3.06,2.81,2.57,P ＜ 0.05).The mRNA level of TrkA expressions increased (t =4.57,3.06,5.39,5.86,P ＜ 0.05),while the mRNA level of TrkB decreased (t =14.87,11.69,4.98,P ＜ 0.05).Conclusions As a signaling pathways downstream of NGF and BDNF,TrkA and TrkB may play an important role in radiation-induced neurogenesis impairment.