Friday, 12 Dec, 2008 Health & Fitness
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Suicide - A Genetical Problem?

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Serious depression can lead to specific changes of DNA in the brain. It changes genes' activeness, which, in its turn, leads to pathological psychic disturbances. This is the conclusion of the scientists who have studied the brains of people who have committed suicide.

Dr Michael Poulter from the University of Western Ontario in Canada and his colleagues from Carleton University and University of Ottawa have studied the brain tissues of 10 people who committed suicide after a period of depression (in medical terms this would be called serious depressive disturbances) and the brain tissues of other 10 people who died as a result of such unnatural deaths as car accidents, pneumonia and heart attacks. All of them were men and women, practically of the same age, all inhabitants of Hungary. Scientists have realized that most of the DNA in the brains of the suiciders was methylated (methylation is a chemical reaction, consisting of adding a methylic group to aminical groups).

These results were obtained by an analysis of the enzyme responsible for the methylation of DNA - DNA-methyltransferaze, and more specifically, by the quantity of RNA (it shows the activity of the coded gene and the synthesis of the enzyme). The brain of people in the first group contained a higher quantity of this enzyme in some of its areas at the same time (this includes the frontal area).

The changes of DNA-methyltransferaze in the human brain indicate that the level of DNA methylation changes too. This means that the genes' activeness changes. Some of them may be stimulated, others – inhibited. Excessive methylation may even block a certain gene or make it work in an inappropriate time and place, since methylation is one of the basic mechanisms of genome's regulation.

Scientists have tried to find out whether there are genes sensible to the changes in DNA methylation. They measured the level of methylation of a concrete gene in the frontal area – GABA-receptor gene. Gamma-aminobutyric acid is a very important neuromediator responsible for the chemical transmission of the nervous impulse from a neuron to another through a synapse, meant for the protection of the central nervous system from too much excitation. The researchers have chosen this gene because their previous works have shown that its activity in the brain of the suiciders is lowered.

A key fragment of this gene in the brain tissues of people in the first group was 4 times more methylated, another fragment – 2 times more. The conclusion was that the change happens only with certain genes. The gene chemically changed in the brain of the suiciders, playing an important role in the work of the brain and in the human behavior. Its reprogramming leads to serious disturbances of the physical and psychic state of a depressed person. Perhaps, this is why people usually commit suicide.

As Michael Poulter affirms, DNA methylation under conditions of stress was known before, but the concrete mechanisms of this reaction and its fatal consequences for people till now were unknown. It is possible that the discovery could help create "suicide-preventing medicine" for persons suffering from serious depressions, reports Biological Psychiatry magazine.

Posted by summer_rain

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