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 Seeing on the Quick: New Insights into Active Vision in the Brain
15.08.2018 | Eberhard Karls Universität Tübingen

nachricht New Approach to Treating Chronic Itch
15.08.2018 | Universität Zürich

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Unraveling the nature of 'whistlers' from space in the lab

A new study sheds light on how ultralow frequency radio waves and plasmas interact

Scientists at the University of California, Los Angeles present new research on a curious cosmic phenomenon known as "whistlers" -- very low frequency packets...

Im Focus: New interactive machine learning tool makes car designs more aerodynamic

Scientists develop first tool to use machine learning methods to compute flow around interactively designable 3D objects. Tool will be presented at this year’s prestigious SIGGRAPH conference.

When engineers or designers want to test the aerodynamic properties of the newly designed shape of a car, airplane, or other object, they would normally model...

Im Focus: Robots as 'pump attendants': TU Graz develops robot-controlled rapid charging system for e-vehicles

Researchers from TU Graz and their industry partners have unveiled a world first: the prototype of a robot-controlled, high-speed combined charging system (CCS) for electric vehicles that enables series charging of cars in various parking positions.

Global demand for electric vehicles is forecast to rise sharply: by 2025, the number of new vehicle registrations is expected to reach 25 million per year....

Im Focus: The “TRiC” to folding actin

Proteins must be folded correctly to fulfill their molecular functions in cells. Molecular assistants called chaperones help proteins exploit their inbuilt folding potential and reach the correct three-dimensional structure. Researchers at the Max Planck Institute of Biochemistry (MPIB) have demonstrated that actin, the most abundant protein in higher developed cells, does not have the inbuilt potential to fold and instead requires special assistance to fold into its active state. The chaperone TRiC uses a previously undescribed mechanism to perform actin folding. The study was recently published in the journal Cell.

Actin is the most abundant protein in highly developed cells and has diverse functions in processes like cell stabilization, cell division and muscle...

Im Focus: Lining up surprising behaviors of superconductor with one of the world's strongest magnets

Scientists have discovered that the electrical resistance of a copper-oxide compound depends on the magnetic field in a very unusual way -- a finding that could help direct the search for materials that can perfectly conduct electricity at room temperatur

What happens when really powerful magnets--capable of producing magnetic fields nearly two million times stronger than Earth's--are applied to materials that...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Within reach of the Universe

08.08.2018 | Event News

A journey through the history of microscopy – new exhibition opens at the MDC

27.07.2018 | Event News

2018 Work Research Conference

25.07.2018 | Event News

 
Latest News

Unraveling the nature of 'whistlers' from space in the lab

15.08.2018 | Physics and Astronomy

Diving robots find Antarctic winter seas exhale surprising amounts of carbon dioxide

15.08.2018 | Earth Sciences

Early opaque universe linked to galaxy scarcity

15.08.2018 | Physics and Astronomy

VideoLinks
Science & Research
Overview of more VideoLinks >>>