Stress damages the movement centers in the brain

Date:
March 8, 2022
Source:
University of Bonn
Summary:
Stress seems to have a negative effect on the learning of
movements - at least in mice. This is the conclusion of a recent
study. According to the study, the neurons of rodents lose some of
their contacts with other neurons after stress. The animals also
developed motor deficits. The results may be useful for earlier
diagnosis and improved therapy of stress-related diseases such as
depression. They also document that stress leaves traces in the
brain - possibly permanent ones.



FULL STORY ========================================================================== Stress seems to have a negative effect on the learning of movements
-- at least in mice. This is the conclusion of a recent study at the
University of Bonn.

According to the study, the neurons of rodents lose some of their
contacts with other neurons after stress. The animals also developed
motor deficits. The results may be useful for earlier diagnosis and
improved therapy of stress- related diseases such as depression. They
also document that stress leaves traces in the brain -- possibly permanent ones. The study appeared in the journal Translational Psychiatry.


========================================================================== Chronically stressed people often show abnormalities in their motor
skills, such as poorer fine motor control. However, how these symptoms
occur has hardly been studied so far. "We investigated this question
in our study," explains Prof. Dr. Valentin Stein from the Institute of Physiology II at the University of Bonn.

The researchers used mice as experimental animals, some of which they
exposed to a stressful situation for a few days. Meanwhile, they used a
special microscopy method to take pictures of the rodents' brains. They
focused on parts of the cerebral cortex responsible for motor control
and learning new movements.

"With our method, it is possible to observe one and the same neuron at different points in time," says Dr. Anne-Kathrin Gellner, a physician
at the Department of Psychiatry and Psychotherapy at Bonn University
Hospital. "We can therefore see whether and how it changes as a result
of stress." Stressed mice lose synapses In fact, the researchers came
across a conspicuous feature: after the stressful situation, the neurons studied lost some of their synapses -- these are the contacts to other
nerve cells. During learning processes, new synapses are usually formed
or existing ones are strengthened. Instead, the stressed rodents lost
up to 15 percent of their contacts.



==========================================================================
At the same time, the animals developed motor learning deficits. For
example, they had to try to grasp a food pellet with one paw and transport
it into their mouths. In the wild, mice use both paws to do this, so
they had to relearn this skill. The non-stressed control group achieved
a success rate of 30 percent after five days. The stressed rodents,
however, only managed to take the food in every tenth attempt.

Mice vary in their sensitivity to stress. Some of them hardly develop any abnormalities after a few days of stress -- they are considered resilient.

Surprisingly, these robust animals had similar difficulties as their
more sensitive peers in learning to grasp with one hand. "It is therefore possible that motor tests are very suitable for detecting stress-related disorders such as depression before other symptoms become apparent,"
hopes Prof. Valentin Stein.

Even resilient animals are not immune Even in resilient animals, moreover,
the number of synapses decreased after the stress event. Unlike their stress-sensitive peers, however, the affected neurons recovered: after
one and a half weeks, the number of synapses was again similar to that
before the stress event and comparable to that in non-stressed control
animals. "Nevertheless, it may well be that psychological stress also
leaves permanent traces on them if it is too long or too frequent,"
worries Stein, who is also a member of the Transdisciplinary Research
Area (TRA) "Life and Health." The researchers also have clues as to
what triggers the loss of synapses: Certain immune cells, the microglia,
were activated in the rodents' brains.

They belong to the so-called phagocytes and can, for example, digest
pathogens or defective cells. It is possible that they are "switched on"
by stress and then attack the contact sites.

The research group also examined the fluid that washes around the
brain and spinal cord. They found certain proteins that can normally
be detected there in neurodegenerative diseases such as Parkinson's
or Alzheimer's. "We therefore believe that stress-related psychiatric
diseases such as depression are also associated with the degradation
of neurons," says Dr. Gellner. "Accordingly, long-term stress -- to
which children are increasingly exposed -- can potentially cause serious
damage to the brain." The Department of Psychiatry and Psychotherapy of
the University Hospital Bonn, the Institute of Nutritional Research
of the University of Potsdam, the Institute of Biochemistry and
Molecular Biology, the Institute of Molecular Psychiatry, and the
Institute of Physiology II (all University of Bonn) were involved in the
study. Dr. Anne-Kathrin Gellner was supported by the BONFOR program of
the Faculty of Medicine.


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


========================================================================== Journal Reference:
1. Anne-Kathrin Gellner, Aileen Sitter, Michal Rackiewicz, Marc
Sylvester,
Alexandra Philipsen, Andreas Zimmer, Valentin Stein. Stress
vulnerability shapes disruption of motor cortical
neuroplasticity. Translational Psychiatry, 2022; 12 (1) DOI:
10.1038/s41398-022-01855-8 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2022/03/220308102845.htm

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