Molecular bases of astrocyte functions at neurovascular interfaces, by Martine Cohen-Salmon

Summary: Astrocytes are the most abundant glial cells in the brain. Although the astrocyte characteristics vary from one region of the brain to another, they all have a large number of processes that ramify into branches and then secondary branchlets. Hence, protoplasmic astrocytes are large, bushy-shaped cells with diameters of ~40-60 μm and volumes of ~10⁴ μm³. Each astrocyte covers a unique domain, and (in humans) contacts up to 2 million synapses. At the synaptic interface, perisynaptic astrocyte processes sense the extracellular interstitial fluid, take up neurotransmitters and ions, and release neuroactive factors. Astrocytes are also in contact with blood vessels; indeed, the latter are entirely sheathed in perivascular astrocyte processes. The astrocytes at this interface modulate the integrity and functions of the blood-brain barrier, immunity, cerebral blood flow, and interstitial fluid drainage. The mechanisms underlying the astrocyte synaptic and vascular influence are critically important. Indeed, dysregulation of the astrocyte functions and interplay with neurons and the vascular system contributes to the development and progression of most neurological diseases. In our recent studies, we showed that mRNA distribution and local translation specific events occur at perivascular and perisynaptic astrocyte interfaces. We proposed that these mechanisms may be crucial to regulate distal astrocyte perivascular and perisynaptic functions.

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