Ultima edizione | Archivio giornali | Archivio tematico | Archivio video

CNR: Alamanacco della Scienza

Archivio

N. 14 - 14 set 2011
ISSN 2037-4801

International info   a cura di Cecilia Migali

Salute

Control of fear in the brain decoded    

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. The discovery is published in Science and shows that both circuits 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.
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. 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.

Per saperne di più: - www.mpg.de/4412596/Decoding_fear