Distribution and possible roles of aquaporin 9 in the brain

Details

Serval ID
serval:BIB_D0172EB81E0B
Type
Article: article from journal or magazin.
Publication sub-type
Review (review): journal as complete as possible of one specific subject, written based on exhaustive analyses from published work.
Collection
Publications
Institution
Title
Distribution and possible roles of aquaporin 9 in the brain
Journal
Neuroscience
Author(s)
Badaut  J., Regli  L.
ISSN
0306-4522
Publication state
Published
Issued date
2004
Peer-reviewed
Oui
Volume
129
Number
4
Pages
971-81
Notes
Journal Article
Research Support, Non-U.S. Gov't
Review
Abstract
Aquaporin 9 (AQP9) is a member of the aquaporin channel family involved in water flux through plasma membranes and exhibits the distinct feature of being also permeable to monocarboxylates, such as lactate, and various solutes, including glycerol, carbamides, purines, pyrimidines, and urea. AQP9 is constitutively expressed at high levels in the liver. In the brain under physiological conditions, AQP9 was first observed in tanycytes, and then in astrocytes. Only recently, its expression was also shown in neurons. Neurons expressing AQP9 are catecholaminergic and glucose sensitive. The expression of neuronal AQP9 can be negatively regulated by insulin and in diabetic animals an increase in AQP9 expression is observed in the catecholaminergic nuclei of the hindbrain, similar to the regulation of AQP9 by insulin in the liver. Furthermore, after transient brain ischemia, AQP9 expression is increased in astrocytes and its regulation may implicate the MAP-kinase pathways stimulated in such pathological conditions. Despite these new data, the exact role of AQP9 in the brain is still unclear. However, we may hypothesize that AQP9 is implicated in brain energy metabolism, as a neutral solute channel. AQP9 could facilitate the diffusion of lactate from the astrocyte to the neuron. In glucose sensitive neurons, diffusion of lactate and glycerol could stimulate these neurons in a similar manner to glucose and could regulate the energy balance. In pathological conditions, induction of AQP9 in astrocytes could participate in the clearance of excess lactate in the extracellular space. These hypotheses concerning the function of brain AQP9 are still speculative and open new areas of investigation.
Keywords
Animals Aquaporins/*metabolism Brain/cytology/*metabolism Catecholamines/metabolism Extracellular Space/physiology Glucose/metabolism Humans Lactic Acid/metabolism Neuroglia/cytology/*metabolism Neurons/cytology/*metabolism
Pubmed
Web of science
Create date
29/01/2008 15:22
Last modification date
20/08/2019 16:50
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