title: Aquaporin-4 expression contributes to decreases in brain water content during mouse postnatal development.
abstract: The water channel protein aquaporin-4 (AQP4) is implicated to facilitate water efflux from the brain parenchyma into the blood and CSF, playing a critical role in maintaining brain water homeostasis. Nevertheless, its contribution to decreases in brain water content during postnatal development remains unknown. A quantitative Western blot analysis was performed to investigate developmental expression of AQP4 in the whole mouse brain and showed that AQP4 expression level in 1 week-old brain was only 21.3% of that in the adult brain, but significantly increased to 67.4% of the adult level by 2 weeks after birth. Statistical analysis demonstrated that increased AQP4 expression partially relates to decreased brain water content in postnatal mice (r(2)=0.92 and P=0.002). Moreover, AQP4 null mice had greater brain water content than littermate controls from 2 weeks up to adult age. Consistently, mature pattern of AQP4 localization at the brain-blood and brain-CSF interfaces were completed at approximately at 2 weeks after birth. In addition, AQP4 expression in the brain stem and hypothalamus was earlier than that in the cerebral cortex and cerebellum, suggesting a brain regional variation in developmental expression of AQP4. These results characterize the developmental feature of AQP4 expression in the postnatal brain and provide direct evidence for a role of AQP4 in postnatal brain water uptake.
authors.affiliation: Jiangsu Key Laboratory of Neurodegeneration, Nanjing Medical University, Jiangsu Province, China.
authors.forename: Xiumiao
authors.initials: X
authors.lastname: Li
authors.forename: Junying
authors.initials: J
authors.lastname: Gao
authors.forename: Jiong
authors.initials: J
authors.lastname: Ding
authors.forename: Gang
authors.initials: G
authors.lastname: Hu
authors.forename: Ming
authors.initials: M
authors.lastname: Xiao
mesh_terms: D000818:Animals; D051401:Aquaporin 4 / Q000378:metabolism*; D015153:Blotting, Western; D001921:Brain / Q000254:growth & development* / Q000378:metabolism*; D006706:Homeostasis / Q000502:physiology*; D007150:Immunohistochemistry; D051379:Mice; D018345:Mice, Knockout; D014867:Water / Q000378:metabolism*
chemical_list: C496031:Aqp4 protein, mouse; D051401:Aquaporin 4; D014867:Water