| Objective To discuss the changes of the astrocyte specific protein in the early phage of brain radiation injuries, the expression of GFAP in the different doses and times points was observed by both immunoreactivity and mRNA levels in the rat hippocampus after whole-brain irradiation. Methods A model of brain radiation-induced injuries was established in the rat after whole-brain irradiation with the single dose of 2Gy,10Gy or 30Gy by 4 MeV electron beam. The irradiated rats were killed at 1,7and 30days after irradiation .The expression of the GFAPmRNA in the hippocampus was analyzed semiquantitatively with RT-PCR.The brain sections were immunohistochemical stained for GFAP.The morphological characters and the number of GFAP cells were recognized. Results No change was observed among the normal,sham-irradiation and 2Gy groups.GFAPmRNA levels increased at 1day and reached a higher level at 30 days. Its induction by irradiation was in a dose-dependent manner with the dose increase, in contrast to 2Gy group, almost 2-fold and 1-fold increases in 30Gy and 10Gy group were observed respectively. A significant increase in GFAP-positive astrocytes with enhanced GFAP immunoreactivity was observed at 30 days after a dose of 10 or 30 Gy,but not after 2Gy. Conclusion The increase of GFAPmRNA levels and immunoreactivity after irradiation was time and dose-dependent, the up-regulation of GFAP-positive astrocytes was later than that of GFAPmRNA.This suggests that the increase of GFAP-positive astrocytes due partly to the enhanced GFAP gene expression and GFAP may play an important role in the mechanisms of early phage of brain radiation-induced injuries. |
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