Astrocytes dynamically regulate the blood-brain barrier in the healthy brain

The blood-brain barrier(BBB)(discovered and defined by Max Lewandowsky and Lina Stern,and not,as it is universally,and yet erroneously believed,by Paul Ehrlich(Verkhratsky and Pivoriunas,2023))that separates the nervous system from the circulation is evolutionarily conserved from arthropods to man.The primeval BBB of the invertebrates and some early vertebrates was made solely by glial cells and secured(in invertebrates)by septate junctions.

Astrocyte chloride,excitatory-inhibitory balance and epilepsy

Excitation and inhibition are at the core of brain function and malfunction.To sustain the activity of neuronal networks over time and space,glutamatergic excitation is balanced by GABAergic inhibition.The equipoise of excitation and inhibition,known as the excitation/inhibition(E/I)balance,is crucial for proper brain function.The E/I balance is highly dynamic and shifts across different brain states:wakefulness primarily augments excitatory activity,while sleep promotes a decrease in excitation and an increase in inhibition(Bridi et al.,2020).Neuronal activity during various brain states is primarily regulated by neurotransmitters(Schiemann et al.,2015),alongside non-synaptic mechanisms that operate on a slower timescale.The non-synaptic mechanisms are many,with the ionic composition of the extracellular space playing a significant role;altering extracellular ion concentrations affects sleep,arousal,electroencephalogram patterns,and behavioral states(Ding et al.,2016).

Astrocytes in human central nervous system diseases: a frontier for new therapies

Astroglia are a broad class of neural parenchymal cells primarily dedicated to homoeostasis and defence of the central nervous system(CNS).Astroglia contribute to the pathophysiology of all neurological and neuropsychiatric disorders in ways that can be either beneficial or detrimental to disorder outcome.Pathophysiological changes in astroglia can be primary or secondary and can result in gain or loss of functions.Astroglia respond to external,non-cell autonomous signals associated with any form of CNS pathology by undergoing complex and variable changes in their structure,molecular expression,and function.In addition,internally driven,cell autonomous changes of astroglial innate properties can lead to CNS pathologies.Astroglial pathophysiology is complex,with different pathophysiological cell states and cell phenotypes that are context-specific and vary with disorder,disorder-stage,comorbidities,age,and sex.Here,we classify astroglial pathophysiology into(i)reactive astrogliosis,(ii)astroglial atrophy with loss of function,(iii)astroglial degeneration and death,and(iv)astrocytopathies characterised by aberrant forms that drive disease.We review astroglial pathophysiology across the spectrum of human CNS diseases and disorders,including neurotrauma,stroke,neuroinfection,autoimmune attack and epilepsy,as well as neurodevelopmental,neurodegenerative,metabolic and neuropsychiatric disorders.Characterising cellular and molecular mechanisms of astroglial pathophysiology represents a new frontier to identify novel therapeutic strategies.

Astrocyte-derived extracellular vesicles mediate intercellular communications of the neurogliovascular unit

The cortical grey matter of mammals has a specific cyto-architecture defined by the process of "tiling" in which protoplasmic astrocytes parcellate the nervous tissue into spatially segregated territorial domains.