Aquaporins in brain edema

Following brain injury, the astrocyte water channel AQP4 mediates edema formation and resolution. Several factors modulate the actions of AQP4 including: (a) AQP4 membrane distribution into arrays, depending on the ratio of AQP4 isoforms; (b) AQP4 interactions with ion channels and gap junctions; (c) temporal variations in AQP4 expression. AbstractBrain edema is a common feature of brain injuries, which leads to increased intracranial pressure (ICP) and ischemia that worsen outcome. Current management of edema focuses on reduction of ICP, but there are no treatments targeting the molecular players directly involved in edema process. The perivascular astrocyte endfeet are critical in maintaining brain homeostasis with ionic and water exchange; in this context, aquaporins (AQPs), astrocyte water channels, have emerged as privileged targets for edema modulation. However, AQPs can facilitate either accumulation or drainage of water, depending on the osmotic gradients between extra ‐intracellular space; and thus inhibition of AQPs leads to different outcomes depending on specific tissue characteristics and time post‐injury. Most of this knowledge has been gathered from the study of AQP4, the best characterized AQP and the one that has the biggest impact on water movement. In addition to the level of expression, the ratio of AQP4 isoforms (m1, m23 or mz), the spatial distribution of AQP4 into orthogonal arrays of particles, and the interaction of AQP4 with neighboring ionic cha...
Source: Journal of Neuroscience Research - Category: Neuroscience Authors: Tags: REVIEW Source Type: research