AQP4 and Alzheimer disease: Considering that Aqp4 mRNA needs to be transported to the terminal endfoot for assembly and late protein translation (Boulay et al., 2017), we further analyzed whether the reduced Apq4 mRNA was more obvious in the endfeet of BBB, which may be evidence of the polar distribution of Aqp4 mRNA in astrocytes and dysfunction of Aqp4 mRNA transport to the endfeet of BBB in AD.