The dynamic changes of nuclear factor-κB during brain injury of irradiated rats / 中华放射医学与防护杂志

ABSTRACT

Objective To investigate the dynamic changes of nuclear factor-κB(NF-κB) during brain injury of irradiated rats.Methods According to the random number table method,82 healthy Sprague-Dawley rats were divided into two groups50 rats in the irradiation group and the other 32 rats in the control group given sham-irradiation.The whole brains of rats in the irradiation group were irradiated with a single dose of 20 Gy electron beam to establish an animal model of radiation-induced brain injury.All brain tissues were respectively taken out 1,3,7,14 and 28 d after irradiation.The quantificational real-time-polymerase chain reaction (QRT-PCR) was used to detect the expressions of the NF-κB mRNA while the expression of NF-κB protein was analyzed by ELISA and Western blot.The positioning expression of NF-κB protein in the hippocampus was measured with immunohistochemical staining.Results In the irradiation group,the expression of NF-κB mRNA significantly increased at 3 and 7 d following irradiation (t =37.79,35.30,P ＜ 0.05) and it approached a peak value on the third day following irradiation.The expression of NF-κB protein in whole brain tissues after irradiation was up-regulated and reached a peak on the first day post-irradiation and it was significantly higher than controls at 1,3,7,14 d after irradiation (t =30.94,14.87,27.17,13.27,P ＜ 0.05) then declined and dropped to the normal level by 28 d.The results of immunohistochemical staining showed that the number of NF-κB positive cells in the hippocampus increased at 1,3 and 7 d following irradiation (t =-8.49,-4.47,-3.46,P ＜ 0.05).Conclusions After irradiation,the expressions of NF-κB mRNA and corresponding protein first increase and then later decrease,which promotes the development of brain injury.