Aquaporin water channels in the brain and molecular mechanisms of brain edema

: Aquaporins(AQPs) are a family of water selective channel. Transcripts of AQP1, AQP3, AQP4, AQP5, AQP8, and AQP9 are detected in the brain. Especially in astrocytes, AQP4 is abundantly expressed in end feet at the blood-brain barrier. Brain AQPs play important roles in the regulation of water homeostasis and the cerebro spinal fluid formation. Recently, AQP4 and AQP9 have been reported to involve in the brain water accumulation in the brain edema. Studies of transgenic mouse and brain injury models reveal that AQP4 may play a role not in the edema formation, but in the fluid elimination. Further study of AQPs functions in the brain may provide new insights into the brain edema and allow the design of novel anti edema medications.