• Astrocyte networks in the mouse brain co

    From ScienceDaily@1:317/3 to All on Tue Mar 8 21:30:40 2022
    Astrocyte networks in the mouse brain control spatial learning and
    memory

    Date:
    March 8, 2022
    Source:
    University of Zurich
    Summary:
    Astrocytes form large networks of interconnected cells in the
    central nervous system. When these cell-to-cell couplings are
    disrupted in the brain of adult mice, the animals are no longer
    able to store spatial information. The astrocytes network is
    thus essential for spatial learning and memory formation, as
    neuroscientists now show.



    FULL STORY ==========================================================================
    In the brain, neurons and astrocytes work together to process information
    and enable complex behavior and cognitive abilities. Astrocytes have many functions like controlling the blood-brain barrier, providing nutrients
    to the nervous tissue, and supporting its repair. An interesting feature
    of astrocytes is that they form large networks of connected cells. These couplings are made of specific membrane pores that are formed by a
    group of proteins called connexins. And through these connections,
    astrocytes can communicate with each other by exchanging various ions
    and small molecules.


    ========================================================================== Switching off astrocyte coupling disrupts spatial memory formation
    A team of neuroscientists led by Aiman Saab and Bruno Weber at the
    Institute of Pharmacology and Toxicology of the University of Zurich
    (UZH), has revealed that in the adult brain of mice astrocyte coupling contributes to neural functioning in the hippocampus, a brain region that
    is involved in spatial memory formation. "We found that in adulthood an
    intact astrocyte network is essential for neural homeostasis, synaptic plasticity and spatial cognitive abilities of this brain region," says
    Aiman Saab, last author of the study.

    To elucidate the functional relevance of the astrocyte network, the
    researchers generated a mouse model in which the two key connexins
    responsible for linking astrocytes together can be selectively
    inactivated. Once the corresponding genes were turned off, the
    astrocytes lost their ability to maintain intercellular networks and astrocyte-to-astrocyte coupling was disrupted within a few weeks.

    Intact astrocytic network is key for brain functioning of adult
    mice Disruption of the astrocyte network altered the excitability
    of the neurons in the hippocampus and their signal transmission
    at the synapses. Moreover, the strengthening of these specialized
    neuronal connections needed to store synaptic information was also
    compromised. This was accompanied by significant deficits in spatial
    learning and memory of the animals. "Astrocyte functions are known to
    be involved in shaping cognitive abilities. Our study now shows that
    an intact astrocyte network is critical for spatial memory formation in
    adult mice," says Ladina Ho"sli, first author of the study.

    Striking similarities to neurodegenerative diseases and neuropsychiatric disorders Furthermore, the primary immune cells of the brain are
    also affected by the loss of astrocyte coupling. The activation of
    these so-called microglia observed in the mice are similar to changes documented in neurodegenerative diseases such as Alzheimer's disease and neuropsychiatric disorders like depressions. "Astrocytes and microglia
    not only changed their morphology, we also found alterations in specific markers that are characteristic to disease- associated microglia,"
    says Ho"sli.

    Since normal brain aging is also associated with changes in astrocytic coupling, these glial changes might contribute to the age-related decline
    in learning and memory. "Our study shows that in the adult brain the functioning of astrocytic connexins and an intact glial network may be important for the way astrocytes and microglia work together to maintain
    neural homeostasis," says Aiman Saab. In a next step, the researchers
    aim to understand how microglial functions are altered when astrocyte
    coupling is perturbed.


    ========================================================================== Story Source: Materials provided by University_of_Zurich. Note: Content
    may be edited for style and length.


    ========================================================================== Journal Reference:
    1. Ladina Ho"sli, Noemi Binini, Kim David Ferrari, Laetitia Thieren
    et. al.

    Decoupling astrocytes in adult mice impairs synaptic plasticity
    and spatial learning. Cell Reports, March 8, 2022 DOI: 10.1016/
    j.celrep.2022.110484 ==========================================================================

    Link to news story: https://www.sciencedaily.com/releases/2022/03/220308115653.htm

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