Differential expression of Egr1 and activation of microglia following irradiation in the rat brain

Henning Vollmann, Sarah Wölfel, Petra Ohneseit, Elke Stransky, Reinhard Vonthein, Wolfgang Wick, Richard Meyermann, Perikles Simon*

*Corresponding author for this work
14 Citations (Scopus)


Background: Little is known about the immediate effects of whole-brain γ-irradiation. The authors hypothesize that Egr1 as an immediate early gene and microglia both participate in early reactions. Material and Methods: Both, expression of Egr1 and cellular distribution were studied in a temporal sequence in different brain regions of rats subjected to irradiation with 10 Gy. Brain tissue was examined using immunohistochemistry, real-time RT-PCR (reverse transcription-polymerase chain reaction), and Western blotting. Results: Astroglia and oligodendroglia showed increased Egr1 immunoreactivity within the first hours following irradiation. This was accompanied by a strong peak in CD68 immunoreactivity histologically attributable to activated microglia. A high constitutive expression of Egr1 protein in the nuclei of activated neurons was reduced following irradiation and RT-PCR demonstrated significantly reduced levels of egr1-lv as a neuronal activity-related mRNA variant. Conclusion: The induction of Egr1 in glial cells, as well as the activation of microglia take place earlier than histological changes reported so far. The authors revealed a temporal sequence of reactions that point toward the initiation of an immediate inflammatory response including reduced neuronal activity.

Original languageEnglish
JournalStrahlentherapie und Onkologie
Issue number5
Pages (from-to)248-255
Number of pages8
Publication statusPublished - 05.2007


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