Fast neutron irradiation induces regionally specific activation of TRAIL/DR5 pathway in rat brain

Object To explore the effects of neutron-irradiation exposure on TRAIL/DR5 pathway in rat brain regions. Methods Fast neutron-irradiation was employed as the irradiated model. The expression changes of TRAIL and DR5 in cerebral cortex, hippocampus, cerebellum and corpus striatum were detected after 1, 7 and 14 d post-irradiation by RT-PCR, ELISA and western blotting. Cleaved caspase-8 was examined by western blotting. Results In protein expression level, TRAIL was increased in the four regions to different extents after 7 d and then recovered after 14 d; DR5 was detected to be up-regulated in cerebral cortex, hippocampus and corpus striatum but down-regulated in cerebellum after 14 d post-irradiation. No significant changes of TRAIL and DR5 were observed in RNA level by RT-PCR. The cleaved caspase-8 was up-expressed the greatest after 1 d in cerebral cortex, hippocampus and cerebellum but continually up-regulated in corpus striatum from 1 to 14 d after irradiation treatment. Conclusion TRAIL was induced in rat brain at early stage while the expression changes of DR5 were delayed by neutron-irradiation and vary in different brain regions. Moreover, caspase-8 was not activated in accord with the changes of TRAIL and DR5 in some brain regions. These indicate that the activation of TRAIL/DR5 pathway plays a role in irradiation-induced injury, which is regulated in a region-specific and time-dependent manner.