Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Control of fear in the brain decoded

06.09.2011
Emotional balance is regulated by molecular factors behind stress response. When healthy people are faced with threatening situations, they react with a suitable behavioural response and do not descend into a state of either panic or indifference, as is the case, for example, with patients who suffer from anxiety.

With the help of genetic studies on mice, scientists from the Max Planck Institute of Psychiatry have discovered two opposing neuronal regulatory circuits for the generation and elimination of fear. Both are controlled by the stress-inducing messenger substance corticotropin-releasing hormone (CRH) and its type 1 receptor (CRHR1).

The availability of these factors in neurons that release glutamate in brain areas of the limbic system activates a neuronal network which causes anxiety behaviour. Conversely, in dopamine-releasing neurons in the mid-brain, these factors give rise to behaviour that reduces fear. Because disorders of the stress factors may be observed in many patients with affective illnesses, the scientists suspect that the pathological alteration of the CRHR1-dependent regulatory circuits may be at the root of such emotional maladies.

An organism’s response to stress is one of the key strategies essential to its survival in dealing with environmental factors. A balanced emotional reaction is of particular importance here and is subject to a highly complex molecular regulation system. Corticotropin-releasing hormone (CRH), which is released in the brain and places the organism in a state of alert, is a central molecular factor of the stress response. In addition to its effect as a hormonal messenger substance, it also controls the activity of neurons through binding to its receptors.

Many patients with anxiety disorders and depression display an altered hormonal stress response and have increased volumes of CRH in the brain. To investigate the underlying pathological processes, the research team working with Jan Deussing at the Max Planck Institute of Psychiatry carried out studies on the mouse model system. This enabled them to selectively deactivate an important factor, for example the CRH type 1 receptor, in certain cells, and thus establish the locations where the receptor is normally active and identify its function.

Using immunohistochemical methods and a series of transgenic mouse lines, the researchers succeeded in mapping the gene activity of the type 1 CRH receptor in the mouse brain in detail for the first time. Interestingly, a specific activity pattern emerged in different neuron groups which release different neuronal messenger substances. In regions of the forebrain (cortex, hippocampus, thalamus, septum), CRHR1 is detectable in glutamatergic and GABAergic neurons. As the limbic system, these regions are linked and, as the current study shows, trigger fear-inducing behaviour in glutamatergic neurons.

In regions of the midbrain (substantia nigra, ventral tegmental area), CRHR1 arises in dopamine-releasing neurons. The functional examination of the mice gave rise to the fairly sensational discovery that the stress hormone CRH actually reduces fear through its receptors in this part of the brain. These neurons demonstrably trigger the direct release of dopamine in regions of the forebrain and hence cause behaviour that overcomes fear.

The opposing effects of the fear-generating and fear-eliminating effect of the CRH/CRHR1 was demonstrated for the first time by this study and prompted the re-evaluation of the use of CRH-receptor antagonists as anxiolytic and antidepressant drugs. The authors speculate that the over-activity of the CRH system in patients with mood disorders is not general but probably limited to certain regulatory circuits in the brain, thus causing imbalanced emotional behaviour. “The use of CRH-receptor 1 antagonists could be particularly useful in patients in who one of these systems is out of sync,” says research group leader Jan Deussing.

Dr. Barbara Meyer | alfa
Further information:
http://www.mpg.de/4412596/Decoding_fear

More articles from Life Sciences:

nachricht Decoding the genome's cryptic language
27.02.2017 | University of California - San Diego

nachricht New risk factors for anxiety disorders
24.02.2017 | Julius-Maximilians-Universität Würzburg

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Safe glide at total engine failure with ELA-inside

On January 15, 2009, Chesley B. Sullenberger was celebrated world-wide: after the two engines had failed due to bird strike, he and his flight crew succeeded after a glide flight with an Airbus A320 in ditching on the Hudson River. All 155 people on board were saved.

On January 15, 2009, Chesley B. Sullenberger was celebrated world-wide: after the two engines had failed due to bird strike, he and his flight crew succeeded...

Im Focus: Breakthrough with a chain of gold atoms

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

Im Focus: DNA repair: a new letter in the cell alphabet

Results reveal how discoveries may be hidden in scientific “blind spots”

Cells need to repair damaged DNA in our genes to prevent the development of cancer and other diseases. Our cells therefore activate and send “repair-proteins”...

Im Focus: Dresdner scientists print tomorrow’s world

The Fraunhofer IWS Dresden and Technische Universität Dresden inaugurated their jointly operated Center for Additive Manufacturing Dresden (AMCD) with a festive ceremony on February 7, 2017. Scientists from various disciplines perform research on materials, additive manufacturing processes and innovative technologies, which build up components in a layer by layer process. This technology opens up new horizons for component design and combinations of functions. For example during fabrication, electrical conductors and sensors are already able to be additively manufactured into components. They provide information about stress conditions of a product during operation.

The 3D-printing technology, or additive manufacturing as it is often called, has long made the step out of scientific research laboratories into industrial...

Im Focus: Mimicking nature's cellular architectures via 3-D printing

Research offers new level of control over the structure of 3-D printed materials

Nature does amazing things with limited design materials. Grass, for example, can support its own weight, resist strong wind loads, and recover after being...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Booth and panel discussion – The Lindau Nobel Laureate Meetings at the AAAS 2017 Annual Meeting

13.02.2017 | Event News

Complex Loading versus Hidden Reserves

10.02.2017 | Event News

International Conference on Crystal Growth in Freiburg

09.02.2017 | Event News

 
Latest News

New pop-up strategy inspired by cuts, not folds

27.02.2017 | Materials Sciences

Sandia uses confined nanoparticles to improve hydrogen storage materials performance

27.02.2017 | Interdisciplinary Research

Decoding the genome's cryptic language

27.02.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>