The study calls into question adult neurogenesis
Until a certain point, scientists were convinced that new neurons in the brain of adult mammals do not appear. Later, first in birds and then in mammals, neurogenesis was confirmed. A new study suggests that neogenesis in an adult is questionable: in any case, its speed is very small, and the continuation of the study of this area may lead to the emergence of new means of its stimulation to combat neurodegenerative diseases.
Neurogenesis - the emergence of new neurons and their migration in the brain. In 1928, the Spanish physician and histologist Santiago Ramon y Cahal , one of the founders of the neural theory, argued that nerve cells are not restored. For a long time, this was perceived as an axiom. The first attempt to refute it failed. In the 1960s, American anatomist Joseph Altman of the Massachusetts University of Technology discovered neurogenesis in adult monkeys, cats, and rats. He discovered this fact by introducing radioactively labeled thymidine into animals - one of the nucleotides that make up DNA: brain cells that included such labeled thymidine, indicated the emergence of new neurons. Publication of the results cost Altman funding and forced to do other research.
Adult neurogenesis began to be taken seriously in the 1980s, when the presence of neurogenesis in the adult brain of songbirds was proved. In the spring, when they begin to sing, thousands of new neurons appear in their brains, which disappear in the fall. Today it is known that in the mammalian brain, neurogenesis occurs in the subventricular zone - the area around the ventricles of the brain - and in the hippocampus. In the first case, the emerged neuroblasts — germinal nerve cells — migrate to the area of the olfactory bulb and turn into adult neurons. In the second, the neurons remain in the same zone responsible for memory and learning. The 1998 Peter Erikson study showed the formation of new neurons in the adult hippocampus.
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In June 2016, Australian researchers found out that humans have proteins that are characteristic of new nerve cells in the brain only in children. One of these proteins, doublecortin, was found only in brain samples of children under 4 years of age. The study does not refute the emergence of new neurons in an adult, but speaks of "functional insignificance" due to low speed. The study used brain samples from 23 people aged from 0.2 to 59 years. The search for marker proteins was carried out in two zones of the hippocampus — subventricular and subgranular.
Presence of doublecortin depending on age
A new study covered the brain samples of 59 people. The “oldest” samples in which new neurons were found belonged to a 13-year-old teenager. In 1 year, the number of new neurons, according to researchers, has already significantly decreased. As in the previous case, the study does not refute neurogenesis in adulthood completely, but it indicates its decline so severe that it questions the possibility of using this factor in the treatment of neurodegenerative diseases. And this, in turn, may lead to the emergence of new means of its stimulation to combat such diseases.
The complete lack of the possibility of neurogenesis in the brain of an adult is also not something negative, this fact may show the difference between a man and a number of other mammals. The head of the team of scientists, Arturo Alvarez-Buylla (Arturo Alvarez-Buylla), who passed all stages of neurogenesis research from proving its existence in animals to denying the important role of this factor in humans, continues to look optimistically at work: “We have been working on adult neurogenesis for so long hard to believe in his absence in humans. So we will continue research and see where it takes us. ”
The scientific work was published in March 2018 in the journal Nature. doi: 10.1038 / d41586-018-02629-3
Neurogenesis - the emergence of new neurons and their migration in the brain. In 1928, the Spanish physician and histologist Santiago Ramon y Cahal , one of the founders of the neural theory, argued that nerve cells are not restored. For a long time, this was perceived as an axiom. The first attempt to refute it failed. In the 1960s, American anatomist Joseph Altman of the Massachusetts University of Technology discovered neurogenesis in adult monkeys, cats, and rats. He discovered this fact by introducing radioactively labeled thymidine into animals - one of the nucleotides that make up DNA: brain cells that included such labeled thymidine, indicated the emergence of new neurons. Publication of the results cost Altman funding and forced to do other research.
Adult neurogenesis began to be taken seriously in the 1980s, when the presence of neurogenesis in the adult brain of songbirds was proved. In the spring, when they begin to sing, thousands of new neurons appear in their brains, which disappear in the fall. Today it is known that in the mammalian brain, neurogenesis occurs in the subventricular zone - the area around the ventricles of the brain - and in the hippocampus. In the first case, the emerged neuroblasts — germinal nerve cells — migrate to the area of the olfactory bulb and turn into adult neurons. In the second, the neurons remain in the same zone responsible for memory and learning. The 1998 Peter Erikson study showed the formation of new neurons in the adult hippocampus.
')
In June 2016, Australian researchers found out that humans have proteins that are characteristic of new nerve cells in the brain only in children. One of these proteins, doublecortin, was found only in brain samples of children under 4 years of age. The study does not refute the emergence of new neurons in an adult, but speaks of "functional insignificance" due to low speed. The study used brain samples from 23 people aged from 0.2 to 59 years. The search for marker proteins was carried out in two zones of the hippocampus — subventricular and subgranular.
Presence of doublecortin depending on age
A new study covered the brain samples of 59 people. The “oldest” samples in which new neurons were found belonged to a 13-year-old teenager. In 1 year, the number of new neurons, according to researchers, has already significantly decreased. As in the previous case, the study does not refute neurogenesis in adulthood completely, but it indicates its decline so severe that it questions the possibility of using this factor in the treatment of neurodegenerative diseases. And this, in turn, may lead to the emergence of new means of its stimulation to combat such diseases.
The complete lack of the possibility of neurogenesis in the brain of an adult is also not something negative, this fact may show the difference between a man and a number of other mammals. The head of the team of scientists, Arturo Alvarez-Buylla (Arturo Alvarez-Buylla), who passed all stages of neurogenesis research from proving its existence in animals to denying the important role of this factor in humans, continues to look optimistically at work: “We have been working on adult neurogenesis for so long hard to believe in his absence in humans. So we will continue research and see where it takes us. ”
The scientific work was published in March 2018 in the journal Nature. doi: 10.1038 / d41586-018-02629-3
Source: https://habr.com/ru/post/371331/
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