The activation of aquaporin-4 (AQP4) is also an important mechanism affecting brain oedema, wherein water molecules enter brain tissues in large quantities through the activated AQP4 and then aggravate brain oedema and neuronal necrosis in cytotoxic cerebral oedema (Huang et al., 2014; Chen J. H. et al., 2016). Here, AQP4 is linked to brain edema.