Intestinal bacteria cause depression - VIDEO PDF Print E-mail
Friday, 14 August 2015 00:14
Gastro-intestinal microflora "remembers" the transferred stress and somehow causes the brain to fall into anxiety and depression. Depressed mood and increased anxiety does not necessarily mean that you are actually all bad - the reason is common psychological state may be intestinal bacteria had happened stress affects the condition of microflora, which is itself then triggers depression. Researchers at McMaster University have experimented with mice newborns: from 3 to 21 days mice every day for three hours separated from their mothers. This procedure is stimulated at the cubs anxiety and depressive behavior; stress effect can be observed also at increased levels of the hormone corticosterone. Because of the stress in mice also increased the level of the neurotransmitter acetylcholine, which in turn has a bad effect on the bowel. The same experiment was repeated with the animals from which all previously expelled gastrointestinal microbes. In this case, the hormonal response to stress was the same, and the digestive system begins to work less, but - in the behavior of "axenic" mice showed no signs of depression and increased anxiety. If bacteria from animals that have grown without any stress, transplanted those who are separated from their mothers, the composition and metabolic activity of the transplanted flora me, "normal" bacteria become "stress", and accordingly also changes the behavior of mice. However, if the stress transferred to the microflora of mice that grew up without any stress, the animals continued to behave normally and no signs of depression in their behavior was not. That is, the stress on the neuroendocrine channels affect the microflora, which gives a return effect on the nervous system. At the same time, to the psychological effects can be seen, the brain itself must have experience of stress, stress alone is not enough here microflora. In other words, the bacteria only maintain and develop depression. Details of the results of the experiments can be found in an article in Nature Communications. The fact that the intestinal symbionts actively communicate with the brain and can affect behavior, biologists say for a long time. For example, in 2011 in the journal PNAS published an article, which describes how the neurochemistry of the brain of mice that grew up with or without bacteria. The differences were, inter alia, proteins necessary for the growth and nutrition of neurons, as well as a number of neurotransmitter levels in certain areas of the brain. In general, the presence or absence of bacteria in the digestive system affected the activity of 40 genes into nerve cells. At the same time, it was concluded that the microflora makes animals more cautious and fearful. And the same group of McMaster University has released a few years ago an article with the same statement - that the microflora influences the type of behavior of the individual. But, maybe, it's because mice and humans, with their much more developed brain, bacteria have no effect on the psyche? It is worth remembering two years ago an article in the journal Gastroenterology, in which researchers from the University of California at Los Angeles described how changes in the gastro-intestinal microflora affect the activity of many different areas of the brain - the human brain. In those experiments involved 36 women 18-55 years old. They are divided into three groups: the first within a month ate twice a day with a mixture of yoghurt bacteria probiotics; the second ate a product similar to yogurt taste and appearance, but without bacteria; The third group is nothing like the yogurt did not receive. Before and after "yogurt period" test done fMRI brain scans, at rest and under emotional stress: A woman shows a photo, and we had to guess what emotion express face in the picture, as well as find a similar emotion in another photo portraits. This task was chosen because tests on animals have shown the influence of the microflora is to work those areas of the brain that are responsible for affects, including the processing of emotions in response to visual information. It was found that women who ate yogurt with probiotics, decreased activity of the insula cortex (and it is among other things responsible for processing the signals from the internal organs, including the stomach), and somatosensory cortex. In general, women with probiotics when the emotionally-oriented tasks using a lot less nerve resources related to cognitive, emotional and sensor networks than those who were left without additional bacteria. When scanning of the brain at rest was found that in the use of probiotics enhanced communication between the key areas of the prefrontal cortex, responsible for consciousness and the central gray matter, responsible for the aggressive behavior. Women who did not receive probiotics, central gray matter was mainly due to the areas of the prefrontal cortex, responsible for emotions and sensual experience. However, general conclusions about the fact that "the bacteria manage people", while it is not necessary to do - right now we can only state the fact that the microflora is really somehow affects the neural architecture of the brain, but how it does it, is not very clear. One possible way - to work with the help of some substances on the vagus nerve, whose processes associated with gut brain. Of course, if the results are confirmed and depression in humans, fight depression will be much easier - just temporarily disinfected own gut with antibiotics.



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