Nerve Growth Factor: What It Is And What Functions It Has
Nerve growth factor is a neurotrophin whose main function is to guarantee the correct functioning of the nervous system through the maintenance and regulation of neuronal processes, especially their growth and survival.
It is found in various parts of the body and has been linked to various functions, some of them frankly surprising. If you want to know more, we invite you to continue reading this article.
Nerve growth factor, better known by its acronym NGF or NGF, is a polypeptide that has been shown to be especially involved in processes such as the growth, development, maintenance and survival of nerve cells
This substance was discovered in 1956 by Rita Levi-Montalcini and Stanley Cohen, who observed that this protein is found in the nervous system of mammals, especially involved in those cells that make up the sympathetic nervous system and the neurons involved in the processes sensory.
What functions does this neurotrophin have?
As can be assumed from its name, nerve growth factor is responsible, above all, for the growth of nerve cells, although it also works to maintain them, make them proliferate and ensure their survival for as long as they are needed.
Its function becomes especially important ensuring that the cells responsible for transmitting the impulse from external stimuli that is, the sensory neurons and those of the sympathetic system can continue to live.
Below we will look in more depth at some of the functions carried out by nerve growth factor.
1. Neuronal proliferation
NGF causes some genes to be expressed, such as the bcl-2 gene, coupling to the TrkA receptor (read as ‘Track’). By doing this, it stimulates the proliferation and survival of the neuron.
The union between NGF and p75 can give rise to two antagonistic processes , since it can both induce the survival of the neuron and its programmed death. This has been seen to vary depending on the area of ​​the nervous system.
2. Proliferation of pancreatic cells
It has been seen that the beta cells of the pancreas can present TrkA and p75 receptors, which have an affinity for nerve growth factor.
It has been proven that a decrease in NGF causes these pancreatic cells to begin to die which suggests that this factor plays a very important role in their survival.
3. Regulation of the immune system
NGF promotes the regulation of immunological processes, whether acquired innately or during the life of the individual.
NGF is released in high doses by mast cells , which induces the growth of axons in nociceptive cells, responsible for detecting harmful stimuli. This increases the sensation of pain in inflamed areas.
4. Ovulation
NGF is found abundantly in semen, which has led several studies to raise the idea that this induces ovulation in certain mammalian species.
Although it has been seen that this could occur in animals such as llamas, in humans it is not so clear if it can exert some type of real function or if it is a phenomenon that once had biological importance but is now something vestigial.
5. Romantic love
It has been seen that People who have been in a romantic relationship for a period of no more than or less than a year have higher concentrations of nerve growth factor than in subjects who are single or have had a partner for longer.
NGF can indirectly stimulate the expression of adrenocorticotrophic hormone (ACTH) in the hypothalamic-pituitary-adrenal axis, increasing the secretion of vasopressin.
In turn, ACTH stimulates the secretion of the stress hormone cortisol. By increasing cortisol in the blood, emotions such as euphoria can be induced, which coincides with the first symptoms of romantic love.
Research results
In animal models it has been seen that nerve growth factor prevents and reduces the damage of degenerative diseases. NGF promotes nerve regeneration in rats. Furthermore, in inflammatory diseases, NGF increases, having the function of reducing the symptoms of inflammation
It has also been seen that it could be involved in the repair of myelin, the substance that is responsible for protecting the interior of the neuron, where the nerve impulse travels. This is why the use of nerve growth factor has been proposed as a treatment to treat and prevent multiple sclerosis. The option of using it in psychiatric disorders has also been raised, such as dementia, depression, schizophrenia, anorexia and bulimia nervosa, autism spectrum disorders and Rett syndrome.
1. Alzheimer’s Disease
Problems when emitting maintenance signals from the neuron when NGF is coupled have been linked to Alzheimer’s disease.
That is why it has been proposed, as a therapeutic tool, to incorporate genetically modified connective tissue cells into the brain of patients so that they secrete nerve growth factor, promoting the growth of new neural fibers.
This treatment with connective cells has been found useful in rescuing nerve cells that were vulnerable to dying because of the disease.
In some patients it has been seen that the therapeutic effects of the treatment lasted almost ten years after its application. The nerve cells managed to maintain a healthy size, and signals were activated to promote their survival.
2. Schizophrenia
Stress and anxiety are precipitating factors in many mental disorders included in the DSM-5, and research suggests that A mood influenced by these two emotions affects NGF levels, in addition to harming cognitive functions Given this, it makes sense that cognitive impairment may be seen in patients with schizophrenia.
It has been seen that patients with this disorder, once they are under treatment with atypical antipsychotics, have NGF levels increase, although this effect has not been seen in those who are treated with typical antipsychotics. Patients on atypical antipsychotics show a more significant cognitive improvement compared to those who do not receive that medication.
The fact that the NGF intervenes in reducing the negative symptoms of schizophrenia
3. Rett syndrome and ASD
In Rett syndrome and autism spectrum disorders (ASD) there are certain differences in the levels of nerve growth factor that can be found in various areas of the patients’ nervous system.
In patients with Rett, lower levels of NGF have been observed in the spinal fluid compared to autistic people, who have normal levels.
Pharmacological therapies to regulate NGF in people with Rett syndrome have been shown to be effective , especially in areas such as motor control and functioning at the cortical level. In addition, this type of treatment improves social communication.
4. Bipolar disorder
In bipolar disorder it has been seen that altered levels of neurotrophins pose problems in brain plasticity. In patients with the disorder it has been seen that have reduced levels of NGF, especially in the manic phase This leads to an irritable mood, increased energy, and a decreased subjective need for sleep.
Low levels of nerve growth factor can be used as a biomarker to understand the patient’s current status.
Patients with bipolar disorder treated with lithium have higher concentrations of NGF in the prefrontal cortex, limbic system, hippocampus, and amygdala.
