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Nerve cells communicate with each other via intricate projections. In brain diseases such as Alzheimer's and Parkinson's these extensions atrophy, thereby causing connectivity problems.
Credit: DZNE/Detlef Friedrich
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November 14, 2014
Source:
DZNE - German Center for Neurodegenerative
Diseases
Summary:
In diseases of the brain, such as Alzheimer's
and Parkinson's, the neurons fail to communicate correctly with each other.
Researchers now report that these connectivity problems can be ascribed to
alterations in the structure of the nerve cells.
In diseases of the brain, such as Alzheimer's
and Parkinson's, the neurons fail to communicate correctly with each other. As
Bonn-based researchers of the German Center for Neurodegenerative Diseases
(DZNE) now report in the journal "Neuron," these connectivity
problems can be ascribed to alterations in the structure of the nerve cells.
For their study, the scientists investigated diseased nerve cells using high
precision methods and subsequently simulated their electrical properties on the
computer. In their view, medical interventions that preserve the structural
integrity of neurons may constitute an innovative strategy for the treatment of
neurodegenerative diseases
Inside the brain, the nerve cells, which are
also called "neurons," are woven into a network in which they relay
signals to one another. Thus, neurons form intricate projections that enable
them to transmit electrical stimuli and synchronize their activity. "However,
in Alzheimer's, Parkinson's and in other diseases of the brain, the nerve cells
tend to atrophy. This is a typical symptom of neurodegenerative
processes," explains Professor Stefan Remy, who leads a research group at
the Bonn site of the DZNE and also works for the Department of Epileptology at
the University Hospital Bonn. "In general, diseased cells have smaller as
well as fewer extensions than healthy cells."
Troubles in Communication
It is also known that the signal transmission
between neurons is disturbed. The nerve cells are hyper-excitable. As a result,
they fire electrical impulses in a succession that could best be described as
hectic. "This activity is somewhat reminiscent of epileptic activity.
However, to date it was unclear how changes in cell morphology and abnormal
function are related," remarks Remy. "We have now found that if the
form changes, this has a direct impact on the cell's electrical properties.
It's just like in an electrical power cord. A thin cord that is also short has
different electrical properties than a cord that's thick and longer. We were
able to show that the hyper-excitability can be explained by changes in the
structure of the neurons."
The neuroscientist emphasizes that this finding
does not rule out other factors, such as alterations in cell metabolism.
"However, our results demonstrate that the dysfunctions and the shape of
the neurons are closely connected. Up until now we were not aware of this
relationship."
Precise Measurements and Computer Simulations
For their study, the scientists combined
experimental research with computer simulations. At first, they examined the
electrical activities of individual neurons as well as those of larger cell
groups. For this purpose, they studied mice, whose brains exhibited
Alzheimer-typical hallmarks. Furthermore, using high-precision microscope
techniques, the scientists determined the dimensions of healthy and diseased
nerve cells. Based upon this structural data, Remy's team created a
three-dimensional model of a single neuron and computed its electrical
properties. In this way the researchers were able to relate cellular
dysfunction to changes in cell morphology.
A General Effect
"Our study focused on Alzheimer's.
However, alterations in cell morphology are typical for all neurodegenerative
diseases. Hence, we assume that the dysfunctions in cellular communication that
manifest in other brain diseases are also resulting from structural changes. We
think that this is a general effect shared by different diseases."
In the opinion of the Bonn-based researcher,
these findings cast a new light on pathological hallmarks. On the other hand,
they could possibly also help with options for treatment. "Our results
indicate that if one protects the structure of nerve cells, one also protects
their functions. Pharmaceuticals aiming specifically at safeguarding the shape
of neurons could potentially have a positive impact on disease progression.
Cell morphology would be a novel approach for therapy," says Remy.
"Moreover, our computer model might prove helpful in studying the effects
of these treatment options and in predicting their outcome."
end text
Story Source:
The above story is based on materials
provided by DZNE - German Center for
Neurodegenerative Diseases. Note: Materials may be edited for
content and length.
end story_source
Journal Reference:
1 Zuzana
Šišková, Daniel Justus, Hiroshi Kaneko, Detlef Friedrichs, Niklas Henneberg,
Tatjana Beutel, Julika Pitsch, Susanne Schoch, Albert Becker, Heinz
von der Kammer, Stefan Remy. Dendritic Structural Degeneration Is
Functionally Linked to Cellular Hyperexcitability in a Mouse Model of
Alzheimer’s Disease. Neuron, 2014; DOI: 10.1016/j.neuron.2014.10.024
end journal_references
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DZNE - German Center for Neurodegenerative
Diseases. "Computer model of nerve cells provides insights into
communication problems." ScienceDaily. ScienceDaily, 14 November 2014.
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