AQP1 and Hydrocephalus: In the rat model of kaolin-induced hydrocephalus, AQP 1 expression decreased dramatically in the early stages of hydrocephalus by about 50% through the mechanism of endocytosis restoration (Wang et al., 2011) Additionally, a marked reduction in AQP1 expression in the choroid plexus epithelium was observed in spontaneously hypertensive rats.