Abstract |
The cerebral edema is a common consequence of many heterogeneous
pathologies, such as trauma, ischemia, infections, and CNS tumors.
Also constitutes an important global cause of morbidity and mortality.
The brain edema is defined as the net increase in the amount of water
contained into the brain parenchyma and according to Igor Klatzo it is
distinguished, based on the pathophysiology, in angiogenic and cytotoxic
edema.
A fundamental cause of development of the vasogenic edema is the
disruption of the blood brain barrier, which is a very complex structure
designed to ensure the almost complete and controlled isolation of the CNS
so as to preserve a stable environment for the operation of the neurons.
The cytotoxic edema, is attributed to the energy depletion of CNS cells,
mainly due to ischemia. The resulting impairment of energy - dependent
pumps of the cell membrane, allows uncontrolled ion flux into the
cytoplasm, by specific ion channels. To restore osmotic equilibrium, water
is moving intracellularly through specific water channels, the aquaporins,
resulting in cell swelling and ultimately in cell death through "oncosis'
process.
The aquaporins are transmembrane proteins with water channel
properties. One of these, AQP4, is predominantly expressed in the
perivascular astrocyte endings and it is responsible for the rapid movement
of water into and out of the cell.
Experimental animal studies with AQP4-null animals, demonstrated that
the specific protein is responsible for the rapid depletion of the fluid
of the
vasogenic edema, while, on the other hand, it is also responsible for the
entry of water into the cells in cytotoxic edema.
Another member of the family of aquaporins, the AQP1, seems to play an
important role in the production and transport of the CSF, which
implements a possible participation in CSF disorders such as hydrocephalus.
The development of specific inhibitors or inductors of aquaporins could be
a hope for a new therapeutic approach of cerebral edema, which however
has not been possible yet.
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