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.
It has also been seen that inappropriate levels of this substance cause diseases, cognitive dysfunction and mood problems.
Below we will go into more detail about what exactly this protein does, some of the disorders in which it has been linked, its mechanism of action and the importance of carrying out physical activity to have good levels of the factor.
Brain-derived neurotrophic factor, better known by its acronym BDNF (brain-derived neurotrophic factor), is a protein, whose gene is located on chromosome 11, which It turns out to be the neurotrophin that has the highest expression in the brain of mammals especially in the cerebral cortex and hippocampus.
These neurotrophins play a very important role during brain development, and continue to exert their action in the plasticity of the nervous system once it has reached maturity.
It has been seen that they play an important role in processes such as neurogenesis, the maintenance and sanitation of the function of neurons and their structural integrity. In fact, Mark Tuszynski of the University of California showed that this was one of the factors that, in animal models, prevented neuronal death when a brain injury occurs
Function of BDNF in the nervous system
Neurotrophic factor acts on certain neurons in the central nervous system and also in the peripheral nervous system, helping the neurons in these places to survive. In addition, it facilitates its growth and differentiation.
This substance It is especially active in parts of the central nervous system, specifically 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 that it can be found in places such as the retina, kidneys, motor neurons, skeletal muscle, prostate and even in saliva.
Brain-derived neurotrophic factor plays an important role in long-term memory Although it is true that a large number of neurons in the mammalian brain are formed during the embryonic state, parts of the individual’s brain, when it is already an adult, have the ability to generate new neurons from neural stem cells. This process is known as neurogenesis. Neurotrophs help stimulate and control this process, with BDNF being the most important.
Mechanism of action
BDNF binds to at least two receptors on the surface of cells, which are capable of responding to this growth factor: Track B (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 like. Research has pointed out that this interaction is what is behind the inhibition of neuronal death.
Cognitive habilyties
Living in environments that have multiple cognitive stimuli, in addition to leading a physically active lifestyle, has been related to having good cognitive function in general. Cognitive, physical and visual stimulation translates into greater neuronal functioning, increasing synaptic communication between neurons, which implies changes in both brain structure and chemistry.
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 having a better memory and learning capacity. This factor would cause more synapses (synaptogenesis), dendrites (dendritogenesis) and, as we were already commenting, greater neurogenesis.
Relationship with pathology
In the same way that brain-derived neurotrophic factor has been associated with better cognitive ability and being behind processes such as learning, memory and thinking, it was inevitable to observe to what extent this factor may be absent in neurodegenerative diseases and disorders. psychiatric. Below we will see a few.
1. Schizophrenia
The fact that BDNF is a crucial substance for the survival of the central and peripheral nervous system, especially in relation to synaptogenesis during and after embryonic development, has led to its relationship with schizophrenia.
It has been seen that People with the diagnosis have lower amounts of the factor in the dorsolateral prefrontal cortex an area related to working memory.
2. Depression
High levels of the stress hormone corticosterone have been linked to a reduction in BDNF expression in animal models, implying atrophy of the hippocampus.
A decrease in activity in the hippocampus and other limbic structures has been linked to mood problems especially with suffering from chronic depression.
On the other hand, it has been seen that the neurotransmitter glutamate, caloric deficit, intellectual and voluntary stimulation, in addition to antidepressants, 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 and later stages of their lives.
As we have already seen, brain-derived neurotrophic factor appears to be a critical substance in brain development both before and after the prenatal period. As we age, BDNF levels decrease in brain tissues
The hippocampal volume is reducing due to this phenomenon, which suggests that this reduction in BDNF implies the cognitive problems so characteristic of old age.
BDNF and physical exercise
In animal models, especially rats, it has been observed that Carrying out moderate physical activity, such as running a kilometer a day, increased BDNF levels in the hippocampus
These changes in the levels of the factor have been especially significant in neurons of the dentate gyrus, the hilus and the CA3 region and appear after just a few days. Other regions in which changes were found were in the cerebellum, cerebral cortex and lumbar spinal cord.
Research carried out with humans has seen that carrying out physical activity helps maintain and even improve brain plasticity, a characteristic characteristic of the hippocampus. Higher functions such as learning or memory are benefited by carrying out healthy habits such as walking thirty minutes a day, do any sport or, and especially, run. Exercise induces greater BDNF gene expression.
