Brain-derived neurotrophic factor (BDNF): what is it?

Brain-derived neurotrophic factor has been shown to be one of the most important neurotrophins in processes such as learning, memory and thinking.

Inadequate levels of this substance have also been shown to lead to illness, cognitive dysfunction, and mood problems.

Below, we’ll go into more detail about what exactly this protein does, some of the disorders it’s been linked to, its mechanism of action, and the importance of physical activity for getting good factor levels.

    What is brain-derived neurotrophic factor?

    Brain-derived neurotrophic factor, better known by its acronym BDNF (brain-derived neurotrophic factor), is a protein, the gene is located on chromosome 11, which it is the neurotrophin that is expressed the most in the brain of mammals, Especially in the cerebral cortex and the hippocampus.

    These neurotrophins play a very important role in the development of the brain, and continue to exert their action on the plasticity of the nervous system once it has reached maturity.

    They have been shown to play an important role in processes such as neurogenesis, maintenance and repair of neuronal function and their structural integrity. In fact, Mark Tuszynski from the University of California proved that it was. one of the factors that in animal models prevented neuronal death from brain injury.

    BDNF function in the nervous system

    The neurotrophic factor acts on certain neurons in the central nervous system and also on the peripheral, helping the neurons in these places to survive. In addition, it facilitates their growth and differentiation.

    this substance it is particularly active in certain parts of the central nervous system, in particular the cerebral cortex, the hippocampus and the most basal part of the brain.. These areas are involved in cognitive processes such as memory, learning, and thinking. It has also been seen in places like the retina, kidneys, motor neurons, skeletal muscles, prostate, and even saliva.

    The brain-derived neurotrophic factor plays an important role in long-term memory. While it is true that a large number of neurons in the brain of mammals are formed during the embryonic state, certain parts of the brain of the individual, when he is an adult, have the capacity to generate new neurons. from neural stem cells. This process is called neurogenesis. Neurotrophs help stimulate and control this process, with BDNF being the most important.

      Action mechanism

      BDNF binds to at least two receptors on the surface of cells that are able to respond to this growth factor: the B pathway (TrkB) and the low affinity receptor for nerve growth factor (LNGFR). Neurotrophic factor modulates the activity of several neurotransmitter receptors, including nicotinic receptors.

      1. TrkB

      TrkB is encoded by the NTRK2 gene. Activation of the BDNF-TrkB pathway is important for short-term memory development and neuronal growth.

      2. LNGFR

      It is not very clear what the interaction between BDNF and the LNGFR receptor is. Research has pointed out that this interaction is what is believed to be behind the inhibition of neuronal death.

      cognitive skills

      Living in environments that have multiple cognitive stimuli, in addition to leading a physically active lifestyle, has been associated with good cognitive function overall. Cognitive, physical and visual stimulation leads to increased neural functioning, an increase in synaptic communication between neurons, which involves changes in the structure and chemistry of the brain.

      Sensory stimuli are first processed by the cortex before reaching the hippocampus. BDNF expression is enhanced in environments rich in cognitive stimuli, Which has been attributed to be the cause of better memory and better learning ability. This factor would lead to more synapses (synaptogenesis), dendrites (dendritogenesis) and, as we mentioned, greater neurogenesis.

      Relationship with pathology

      Just as the brain-derived neurotrophic factor has been associated with improved cognitive ability and being behind processes such as learning, memory, and thinking, it was inevitable to observe how much of this factor may be absent in human beings. neurodegenerative diseases and psychiatric disorders. Below we will see a few of them.

      1. Schizophrenia

      The fact that BDNF is a crucial substance for the survival of the central and peripheral nervous system, particularly in relation to synaptogenesis during and after embryonic development, has led to its association with schizophrenia.

      We saw that people with the diagnosis have lower amounts of the factor in the dorsolateral prefrontal cortex, An area linked to working memory.

      2. Depression

      It has been associated with elevated levels of the stress hormone corticosterone, with reduced expression of BDNF in animal models, implicating atrophy of the hippocampus.

      Decreased activity in the hippocampus and other limbic structures has been linked to mood problems., Especially with chronic depression.

      On the other hand, the glutamate neurotransmitter, calorie deficit, intellectual and voluntary stimulation, in addition to antidepressants, have been shown to increase the expression of BDNF in the brain and reduce depressive symptoms.

      3. Aging

      BDNF levels are highly regulated throughout people’s lives, both in the early stages and in the later stages of life.

      As we have seen, brain-derived neurotrophic factor is found to be an essential substance in brain development before and after the prenatal period. As we age, the levels of BDNF decrease in brain tissue..

      The hippocampal volume is decreasing due to this phenomenon, suggesting that this reduction in BDNF involves such characteristic cognitive problems in old age.

        BDNF and exercise

        In animal models, especially with rats, it has been observed that moderate physical activity, such as running a mile a day, increased BDNF levels in the hippocampus..

        These changes in factor levels have been shown to be particularly significant in neurons of the dentate gyrus, hilum, and CA3 region, and manifest themselves within days. Other regions where changes were found were in the cerebellum, cerebral cortex, and lumbar spinal cord.

        Research in humans has shown that participating in physical activity helps maintain and even improve brain plasticity, a characteristic very characteristic of the hippocampus. Higher functions such as learning or memory are improved by adopting healthy habits such as walking for thirty minutes a day., Practice any sport or, above all, run. Exercise induces increased expression of the GDNF gene.

        Bibliographical references:

        • Maisonpierre PC, Le Beau MM, Espinosa R, et al. (1991). Human brain and rat-derived neurotrophic factor and neurotrophin-3: gene structures, chromosome distributions and locations. Genomics 10 (3): 558-68.
        • Soppet, D; Escandon, E; Maragos, J; et al. (1991). Neurotrophic Factors Brain-derived neurotrophic factor and neurotrophin-3 are ligands for the trkB receptor tyrosine kinase. Cell 65 (5): 895-903.

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