Date:
September 16, 2014
Source:
University of Copenhagen – The Faculty of Health and Medical Sciences
Summary:
Using advanced computer models, neuroscience researchers have gained new knowledge about the complex processes that cause Parkinson's disease. Scanning the brain of a patient suffering from Parkinson's disease reveals that in spite of dopamine cell death, there are no signs of a lack of dopamine -- even at a comparatively late stage in the process.
The defining symptoms of Parkinson's
disease are slow movements, muscular stiffness and shaking. There is currently
no cure for the condition, so it is essential to conduct innovative research
with the potential to shed some light on this terrible disruption to the
central nervous system that affects one person in a thousand in Denmark.
Dopamine is an important
neurotransmitter which affects physical and psychological functions such as
motor control, learning and memory. Levels of this substance are regulated by
special dopamine cells. When the level of dopamine drops, nerve cells that
constitute part of the brain's 'stop signal' are activated.
"This stop signal is rather like
the safety lever on a motorised lawn mower: if you take your hand off the
lever, the mower's motor stops. Similarly, dopamine must always be present in
the system to block the stop signal. Parkinson's disease arises because for
some reason the dopamine cells in the brain are lost, and it is known that the
stop signal is being over-activated somehow or other. Many researchers have
therefore considered it obvious that long-term lack of dopamine must be the
cause of the distinctive symptoms that accompanies the disease. However, we can
now use advanced computer simulations to challenge the existing paradigm and
put forward a different theory about what actually takes place in the brain
when the dopamine cells gradually die," explains Jakob Kisbye Dreyer,
Postdoc at the Department of Neuroscience and Pharmacology, University of
Copenhagen.
A thorn in the side
Scanning the brain of a patient
suffering from Parkinson's disease reveals that in spite of dopamine cell
death, there are no signs of a lack of dopamine -- even at a comparatively late
stage in the process.
"The inability to establish a lack
of dopamine until advanced cases of Parkinson's disease has been a thorn in the
side of researchers for many years. On the one hand, the symptoms indicate that
the stop signal is over-activated, and patients are treated accordingly with a
fair degree of success. On the other hand, data prove that they are not lacking
dopamine," says Postdoc Jakob Kisbye Dreyer.
Computer models predict the progress of
the disease
"Our calculations indicate that
cell death only affects the level of dopamine very late in the process, but
that symptoms can arise long before the level of the neurotransmitter starts to
decline. The reason for this is that the fluctuations that normally make up a
signal become weaker. In the computer model, the brain compensates for the shortage
of signals by creating additional dopamine receptors. This has a positive
effect initially, but as cell death progresses further, the correct signal may
almost disappear. At this stage, the compensation becomes so overwhelming that
even small variations in the level of dopamine trigger the stop signal -- which
can therefore cause the patient to develop the disease."
The new research findings may pave the
way for earlier diagnosis of Parkinson's disease.
Story Source:
The above story is based on materials
provided by University of Copenhagen – The
Faculty of Health and Medical Sciences. Note: Materials may
be edited for content and length.
Journal Reference:
1. J. K. Dreyer. Three Mechanisms by
which Striatal Denervation Causes Breakdown of Dopamine Signaling. Journal
of Neuroscience, 2014; 34 (37): 12444 DOI: 10.1523/JNEUROSCI.1458-14.2014
Cite This Page:
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MLA
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University of Copenhagen – The Faculty
of Health and Medical Sciences. "Myth about Parkinson's disease
debunked." ScienceDaily. ScienceDaily, 16 September 2014.
<www.sciencedaily.com/releases/2014/09/140916084909.htm>.
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