Figure 1.

Pathophysiological responses of radiation-induced brain injury include (1) neuroinflammation, which is associated with increased expression of the transcription factor, nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), as well as upregulated expression of interleukin-1 (IL-1)β, tumor necrosis factor α (TNF-α), interferon γ (INF-γ) and transforming growth factor β (TGF-β); (2) apoptosis of oligodendrocytes and neurons; (3) epigenetic alterations which are associated with DNA double-strand breaks (DSBs), DNA single-strand breaks (SSBs) and DNA hypomethylation; (4) endothelial cell loss and increased blood–brain barrier (BBB) permeability and (5) histopathological changes, including cell necrosis, glial atrophy and demyelination.