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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