Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Vicious circle leads to loss of brain cells in old age

03.09.2018

The so-called CB1 receptor is responsible for the intoxicating effect of cannabis. However, it appears to act also as a kind of “sensor” with which neurons measure and control the activity of certain immune cells in the brain. A recent study by the University of Bonn at least points in this direction. If the sensor fails, chronic inflammation may result - probably the beginning of a dangerous vicious circle. The publication appears in the journal “Frontiers in Molecular Neuroscience”.

The activity of the so-called microglial cells plays an important role in brain aging. These cells are part of the brain’s immune defense: For example, they detect and digest bacteria, but also eliminate diseased or defective nerve cells. They also use messenger substances to alert other defense cells and thus initiate a concerted campaign to protect the brain: an inflammation.


Dr. Andras Bilkei-Gorzo and his colleagues have determined how endocannabinoids attenuate inflammatory reactions in the brain.

© Photo: Kerstin Nicolai/Uni Bonn

This protective mechanism has undesirable side effects; it can also cause damage to healthy brain tissue. Inflammations are therefore usually strictly controlled. “We know that so-called endocannabinoids play an important role in this”, explains Dr. Andras Bilkei-Gorzo from the Institute of Molecular Psychiatry at the University of Bonn. “These are messenger substances produced by the body that act as a kind of brake signal: They prevent the inflammatory activity of the glial cells.”

Endocannabinoids develop their effect by binding to special receptors. There are two different types, called CB1 and CB2. “However, microglial cells have virtually no CB1 and very low level of CB2 receptors,” emphasizes Bilkei-Gorzo. “They are therefore deaf on the CB1 ear. And yet they react to the corresponding brake signals - why this is the case, has been puzzling so far.”

Neurons as “middlemen”

The scientists at the University of Bonn have now been able to shed light on this puzzle. Their findings indicate that the brake signals do not communicate directly with the glial cells, but via middlemen - a certain group of neurons, because this group has a large number of CB1 receptors. “We have studied laboratory mice in which the receptor in these neurons was switched off,” explains Bilkei-Gorzo. “The inflammatory activity of the microglial cells was permanently increased in these animals."

In contrast, in control mice with functional CB1 receptors, the brain's own defense forces were normally inactive. This only changed in the present of inflammatory stimulus. “Based on our results, we assume that CB1 receptors on neurons control the activity of microglial cells,” said Bilkei-Gorzo. “However, we cannot yet say whether this is also the case in humans.”

This is how it might work in mice: As soon as microglial cells detect a bacterial attack or neuronal damage, they switch to inflammation mode. They produce endocannabinoids, which activate the CB1 receptor of the neurons in their vicinity. This way, they inform the nerve cells about their presence and activity. The neurons may then be able to limit the immune response. The scientists were able to show that neurons similarly regulatory the other major glial cell type, the astroglial cells.

During ageing the production of cannabinoids declines reaching a low level in old individuals. This could lead to a kind of vicious circle, Bilkei-Gorzo suspects: “Since the neuronal CB1 receptors are no longer sufficiently activated, the glial cells are almost constantly in inflammatory mode. More regulatory neurons die as a result, so the immune response is less regulated and may become free-running.”

It may be possible to break this vicious circle with drugs in the future. It is for instance hoped that cannabis will help slow the progression of dementia. Its ingredient, tetrahydrocannabinol (THC), is a powerful CB1 receptor activator - even in low doses free from intoxicating effect. Last year, the researchers from Bonn and colleagues from Israel were able to demonstrate that cannabis can reverse the aging processes in the brains of mice. This result now suggest that an anti-inflammatory effect of THC may play a role in its positive effect on the ageing brain.

Publication: Frank Ativie, Joanna A. Komorowska, Eva Beins, Önder Albayram, Till Zimmer, Andreas Zimmer, Dario Tejera, Michael Heneka and Andras Bilkei-Gorzo: Cannabinoid 1 Receptor Signaling on Hippocampal GABAergic Neurons Influences Microglial Activity; Frontiers in Molecular Neuroscience

Wissenschaftliche Ansprechpartner:

Dr. Andras Bilkei-Gorzo
Institute of Molecular Psychiatry
University of Bonn
Tel. +49 (0)228-6885317
E-mail: abilkei@uni-bonn.de

Originalpublikation:

https://doi.org/10.3389/fnmol.2018.00295

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

More articles from Health and Medicine:

nachricht Lighting up cardiovascular problems using nanoparticles
10.12.2019 | University of Southern California

nachricht Lung images of twins with asthma add to understanding of the disease
06.12.2019 | University of Western Ontario

All articles from Health and Medicine >>>

The most recent press releases about innovation >>>

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

Im Focus: How to induce magnetism in graphene

Graphene, a two-dimensional structure made of carbon, is a material with excellent mechanical, electronic and optical properties. However, it did not seem suitable for magnetic applications. Together with international partners, Empa researchers have now succeeded in synthesizing a unique nanographene predicted in the 1970s, which conclusively demonstrates that carbon in very specific forms has magnetic properties that could permit future spintronic applications. The results have just been published in the renowned journal Nature Nanotechnology.

Depending on the shape and orientation of their edges, graphene nanostructures (also known as nanographenes) can have very different properties – for example,...

Im Focus: Electronic map reveals 'rules of the road' in superconductor

Band structure map exposes iron selenide's enigmatic electronic signature

Using a clever technique that causes unruly crystals of iron selenide to snap into alignment, Rice University physicists have drawn a detailed map that reveals...

Im Focus: Developing a digital twin

University of Texas and MIT researchers create virtual UAVs that can predict vehicle health, enable autonomous decision-making

In the not too distant future, we can expect to see our skies filled with unmanned aerial vehicles (UAVs) delivering packages, maybe even people, from location...

Im Focus: The coldest reaction

With ultracold chemistry, researchers get a first look at exactly what happens during a chemical reaction

The coldest chemical reaction in the known universe took place in what appears to be a chaotic mess of lasers. The appearance deceives: Deep within that...

Im Focus: How do scars form? Fascia function as a repository of mobile scar tissue

Abnormal scarring is a serious threat resulting in non-healing chronic wounds or fibrosis. Scars form when fibroblasts, a type of cell of connective tissue, reach wounded skin and deposit plugs of extracellular matrix. Until today, the question about the exact anatomical origin of these fibroblasts has not been answered. In order to find potential ways of influencing the scarring process, the team of Dr. Yuval Rinkevich, Group Leader for Regenerative Biology at the Institute of Lung Biology and Disease at Helmholtz Zentrum München, aimed to finally find an answer. As it was already known that all scars derive from a fibroblast lineage expressing the Engrailed-1 gene - a lineage not only present in skin, but also in fascia - the researchers intentionally tried to understand whether or not fascia might be the origin of fibroblasts.

Fibroblasts kit - ready to heal wounds

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

The Future of Work

03.12.2019 | Event News

First International Conference on Agrophotovoltaics in August 2020

15.11.2019 | Event News

Laser Symposium on Electromobility in Aachen: trends for the mobility revolution

15.11.2019 | Event News

 
Latest News

City research draws on Formula 1 technology for the construction of skyscrapers

10.12.2019 | Architecture and Construction

Reorganizing a computer chip: Transistors can now both process and store information

10.12.2019 | Information Technology

Could dark carbon be hiding the true scale of ocean 'dead zones'?

10.12.2019 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>