Radiation attenuates physiological angiogenesis by differential expression of VEGF, Ang-1, tie-2 and Ang-2 in rat brain

Radiat Res. 2011 Dec;176(6):753-60. doi: 10.1667/rr2647.1. Epub 2011 Sep 30.


The etiology of radiation-induced cerebrovascular rarefaction remains unknown. In the present study, we examined the effect of whole-brain irradiation on endothelial cell (EC) proliferation/apoptosis and expression of various angiogenic factors in rat brain. F344 × BN rats received either whole-brain irradiation (a single dose of 10 Gy γ rays) or sham irradiation and were maintained for 4, 8 and 24 h after irradiation. Double immunofluorescence staining was employed to visualize EC proliferation/apoptosis in brain. The mRNA and protein expression levels of vascular endothelial growth factor (VEGF), angiopoietin-1 (Ang-1), endothelial-specific receptor tyrosine kinase (Tie-2), and Ang-2 in brain were determined by real-time RT-PCR and immunofluorescence staining. A significant reduction in CD31-immunoreactive cells was detected in irradiated rat brains compared with sham-irradiated controls. Whole-brain irradiation significantly suppressed EC proliferation and increased EC apoptosis. In addition, a significant decrease in mRNA and protein expression of VEGF, Ang-1 and Tie-2 was observed in irradiated rat brains. In contrast, whole-brain irradiation significantly upregulated Ang-2 expression in rat brains. The present study provides novel evidence that whole-brain irradiation differentially affects mRNA and protein expression of VEGF, Ang-1, Tie-2 and Ang-2. These changes are closely associated with decreased EC proliferation and increased EC apoptosis in brain.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Angiopoietin-1 / genetics*
  • Angiopoietin-2 / genetics*
  • Animals
  • Apoptosis / radiation effects
  • Brain / cytology
  • Brain / metabolism
  • Brain / radiation effects*
  • Cell Proliferation / radiation effects
  • Endothelial Cells / cytology
  • Endothelial Cells / metabolism
  • Endothelial Cells / radiation effects
  • Gene Expression Regulation / radiation effects*
  • Male
  • Neovascularization, Physiologic / radiation effects*
  • Rats
  • Receptor, TIE-2 / genetics*
  • Vascular Endothelial Growth Factor A / genetics*


  • Angiopoietin-1
  • Angiopoietin-2
  • Vascular Endothelial Growth Factor A
  • Receptor, TIE-2