Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Epilepsy: When the neuron's doorman allows too much in

19.11.2015

In epilepsy, nerve cells or neurons lose their usual rhythm, and ion channels, which have a decisive influence on their excitability, are involved. A team of researchers under the direction of the University of Bonn has now discovered a new mechanism for influencing ion channels in epilepsy. They found that spermine inside neurons dampens the neurons excitability. In epilepsy, spermine levels decrease, causing hyperexcitability. The researchers hope that their findings can be exploited to develop new therapies for epilepsies. They are reporting their findings in "The Journal of Neuroscience".

In Germany, approximately one out of a hundred people suffer from epilepsy and one out of twenty suffer a seizure at least once during their lifetime. Seizures occur when many nerve cells in the brain fire in synchrony.


This is how a neuron from the hippocampus of a rat looks like. The cell and it's extenive processes are visulaised using a fluorescent dye, filled via a glass pipette.

(c) Photo: AG Heinz Beck/Uni Bonn

Scientists are searching for the causes leading to this simultaneous excitation of brain cells. Researchers at the Department of Epileptology, the Institute for Neuropathology and the Institute for Molecular Psychiatry, together with the Caesar Research Center and the Hebrew University (Israel) have discovered a mechanism which previously was not thought to be involved in the development of epilepsy.

"Doormen" determine how many sodium ions are allowed in

Neurons integrate many inputs together to then determine an appropriate output, and sodium channels play a key role in both processes. "They play an important role in the excitation of nerve cell axons and signal transfer between various cells," says Prof. Dr. Heinz Beck, who conducts research in experimental epileptology at the Department of Epileptology, at the Life & Brain center and the German Center for Neurodegenerative Diseases (DZNE).

Like a type of door, sodium channels allow sodium ions to flow into nerve cells through tiny pores. They consist of large protein complexes located in the membranes of nerve cells. The scientists found a large increase in a certain sodium influx which significantly increased the excitability of cells in the epileptic animal.

For this reason, scientists working with Prof. Beck initially compared the sodium channel proteins from the brains of epileptic rats to those of healthy animals. "However, this did not reveal any increased formation of sodium channel proteins, which could have explained the overexcitation of nerve cells." reports the epilepsy researcher.

After a long search, the team of researchers found a completely different group of substances: the polyamines. Spermine belongs to this group; it is produced in cells and plugs the pores of the sodium channels from within. like a doorman. In this case, the influx of sodium ions is blocked and the excitation of the nerve cells is reduced.

Overexcitation is attenuated through administration of spermine

The scientists investigated how much of the seizure-inhibiting substance is present in the nerve cells of rats suffering from epilepsy and compared the values to those of healthy animals. "The amount of spermine in the cells of the hippocampus was significantly reduced in diseased animals as compared to the healthy animals," report the lead authors Dr. Michel Royeck and Dr. Thoralf Optiz from Dr. Beck's team. “Furthermore, the reduced spermine in the nerve cell led to increased excitability; the cells were more sensitive to input and generated more output” said fellow lead author Dr. Tony Kelly. The investigators tested this important finding, compensating for the deficiency in the nerve cells of epileptic rats by adding spermine back into the cell. As a result, the increase in sodium currents was reversed and the excitability of the neuron returned to normal.

The lower level of spermine in the epileptic rat’s brain was evidently caused by an upregulation of spermidine/spermine-N(1)-acetyltransferase. This enzyme breaks down the spermine which is important in the control of sodium channels. According to the scientists, this result could be a potential starting point for novel epilepsy therapies. "If a substance was available to reduce the activity of acetyltransferase back to normal levels, the lack of spermine and thus the symptoms of epilepsy could be mitigated," speculates Prof. Beck. However, concrete therapeutic applications are still a long way off.

Publication: Downregulation of Spermine Augments Dendritic Persistent Sodium Currents and Synaptic Integration after Status Epilepticus, The Journal of Neuroscience, DOI: 10.1523/JNEUROSCI.0493-15.2015

Media contact information:

Prof. Dr. Heinz Beck
University Hospital for Epileptology, Life & Brain Center,
German Center for Neurodegenerative Diseases
Spokesperson for Collaborative Research Center 1089
Tel. ++49-228-6885215
E-Mail: Heinz.Beck@ukb.uni-bonn.de

Dr. Tony Kelly
University Hospital for Epileptology, Life & Brain Center,
Tel. ++49-228-6885276
E-Mail: tony.kelly@ukb.uni-bonn.de

Johannes Seiler | idw - Informationsdienst Wissenschaft
Further information:
http://www.uni-bonn.de

More articles from Life Sciences:

nachricht Researchers identify potentially druggable mutant p53 proteins that promote cancer growth
09.12.2016 | Cold Spring Harbor Laboratory

nachricht Plant-based substance boosts eyelash growth
09.12.2016 | Fraunhofer-Institut für Angewandte Polymerforschung IAP

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Electron highway inside crystal

Physicists of the University of Würzburg have made an astonishing discovery in a specific type of topological insulators. The effect is due to the structure of the materials used. The researchers have now published their work in the journal Science.

Topological insulators are currently the hot topic in physics according to the newspaper Neue Zürcher Zeitung. Only a few weeks ago, their importance was...

Im Focus: Significantly more productivity in USP lasers

In recent years, lasers with ultrashort pulses (USP) down to the femtosecond range have become established on an industrial scale. They could advance some applications with the much-lauded “cold ablation” – if that meant they would then achieve more throughput. A new generation of process engineering that will address this issue in particular will be discussed at the “4th UKP Workshop – Ultrafast Laser Technology” in April 2017.

Even back in the 1990s, scientists were comparing materials processing with nanosecond, picosecond and femtosesecond pulses. The result was surprising:...

Im Focus: Shape matters when light meets atom

Mapping the interaction of a single atom with a single photon may inform design of quantum devices

Have you ever wondered how you see the world? Vision is about photons of light, which are packets of energy, interacting with the atoms or molecules in what...

Im Focus: Novel silicon etching technique crafts 3-D gradient refractive index micro-optics

A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.

Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...

Im Focus: Quantum Particles Form Droplets

In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.

“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ICTM Conference 2017: Production technology for turbomachine manufacturing of the future

16.11.2016 | Event News

Innovation Day Laser Technology – Laser Additive Manufacturing

01.11.2016 | Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

 
Latest News

Researchers identify potentially druggable mutant p53 proteins that promote cancer growth

09.12.2016 | Life Sciences

Scientists produce a new roadmap for guiding development & conservation in the Amazon

09.12.2016 | Ecology, The Environment and Conservation

Satellites, airport visibility readings shed light on troops' exposure to air pollution

09.12.2016 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>