UC Riverside

Aquaporin-4 (AQP4) is the glial water channel that is primarily expressed in astrocytes. Various roles of AQP4 have been previously discussed such as deletion of AQP4 induces enlarged extracellular space. However, the role of AQP4 in brain water diffusivity is not well described. In this study, we investigated the developmental changes of brain water diffusivity in relation to development and presence of AQP4 channels in AQP4+/+ and AQP4-/- animals using diffusion tensor imaging (DTI) and brain water content analyses. DTI results revealed a developmental decrease in water diffusivity in both AQP4+/+ and AQP4-/- genotypes. AQP4-/- mice exhibited an increased diffusivities as juveniles but later deceased in adulthood. Brain water content analysis revealed greater water content in AQP4-/- mice, which suggests the effect of enlarged extracellular space resulting in greater basal water content. The results highlight the role of AQP4 channels in the regulation and mediation of brain water mobility.