Nerve growth factor: what is it and what functions it has

Nerve growth factor is a neurotrophin the main function is to ensure the proper functioning of the nervous system by maintaining and regulating neuronal processes, in particular their growth and survival.

It is found in various parts of the body and has been linked to various functions, some of which are downright amazing. If you want to know more, we invite you to continue reading this article.

    What is the nerve growth factor?

    Nerve growth factor, better known by its acronym NGF or FCN, is a polypeptide that has been shown to be particularly 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, particularly involved in the cells that make up the sympathetic nervous system and neurons involved in sensory processes. .

    What functions does this neurotrophin perform?

    As the name suggests, nerve growth factor is primarily responsible for the growth of nerve cells, although it also works to maintain them, proliferate them, and ensure their survival for as long as it takes.

    Its function becomes particularly important ensure that the cells responsible for transmitting the impulse of external stimuliIn other words, sensory neurons and those of the sympathetic system can continue to live.

    Below we will take a closer look at some of the functions performed by the nerve growth factor.

    1. Neural proliferation

    NGF causes the expression of certain genes, such as the bcl-2 gene, by binding to the TrkA receptor (read by “Track”). In doing so, it stimulates the proliferation and survival of the neuron.

    Binding between NGF and p75 may lead to two antagonistic processes, Since it can induce both neuron survival and programmed death. It has been shown to vary depending on the area of ​​the nervous system.

      2. Proliferation of pancreatic cells

      Beta cells in the pancreas have been shown to have TrkA and p75 receptors, which have an affinity for nerve growth factor.

      It has been proven that a decrease in NGF causes the death of these pancreatic cells, Which suggests that this factor plays a very important role in their survival.

      3. Regulation of the immune system

      NGF promotes the regulation of immune processes, whether acquired innately or during an individual’s lifetime.

      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 the inflamed areas.

      4. Ovulation

      NGF is found in abundance in semen, which has led several studies to suggest that it induces ovulation in certain species of mammals.

      Although it has been seen that this can occur in animals such as flames, in humans it is not so clear whether it can perform a real function or whether it is a a phenomenon which once had its biological importance but which is now a residual thing.

      5. Romantic love

      We saw that people who have been in a love affair for less than a year have higher concentrations of the nerve growth factor than in single subjects or in a relationship for a longer time.

      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 cortisol, a stress hormone. The increase in cortisol in the blood can induce emotions such as euphoria, which coincides with the first symptoms of romantic love.

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      In animal models, the nerve growth factor has been shown to prevent and reduce damage from degenerative diseases. NGF promotes nerve regeneration in rats. In addition, in inflammatory diseases, NGF increases, causing the function of reducing the symptoms of inflammation.

      We have also seen that it could be involved in the repair of myelin, the substance which is responsible for protecting the interior of the neuron, where nerve impulses move. This is why the use of nerve growth factor as a treatment to treat and prevent multiple sclerosis has been proposed. The possibility of using it in psychiatric disorders such as dementia, depression, schizophrenia, anorexia and bulimia nervosa, autism spectrum disorders and Rett syndrome has also been considered.

      1. Alzheimer’s disease

      Problems emitting maintenance signals from the neuron when the NGF is coupled have been linked to Alzheimer’s disease.

      This is why it has been proposed, as a therapeutic tool, to incorporate into the brain of patients genetically modified connective tissue cells because they secrete nerve growth factor, promoting the growth of new neural fibers.

      This connective cell treatment has been found to be helpful in saving nerve cells vulnerable to death. due to illness.

      In some patients, the therapeutic effects of the treatment have been seen to last almost ten years after its application. The nerve cells have managed to maintain a healthy size and signals have been activated to promote their survival.

        2. Schizophrenia

        Stress and anxiety are triggers in many mental disorders listed by the DSM-5, and research suggests that a mood influenced by these two emotions affects NGF levels and impairs cognitive functions. With that in mind, it makes sense that cognitive impairment could be observed in patients with schizophrenia.

        Patients with this disorder have been shown to increase their NGF levels once they are treated with atypical antipsychotics, although this effect has not been seen in those treated with typical antipsychotics. Patients with atypical antipsychotics show more significant cognitive improvement than those who do not receive this drug.

        The fact that the NGF is involved in reduction of the negative symptomatology of schizophrenia.

        3. Rett syndrome and ASD

        In Rett syndrome and Autism Spectrum Disorder (ASD), there are certain differences in the levels of nerve growth factor that can be found in various areas of the nervous system of patients.

        In patients with Rett’s, lower levels of NGF in the cerebrospinal fluid were observed compared to autistic people, those with properly 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 cortical functioning. In addition, this type of treatment improves social communication.

        4. Bipolar disorder

        In bipolar disorder, altered neurotrophin levels have been shown to cause problems with brain plasticity. In patients with the disorder, it has been observed that they have / display reduced levels of NGF, especially in the manic phase. This leads to an irritable mood, greater energy, and a less subjective need for sleep.

        Low levels of nerve growth factor can be used as a biomarker to know the patient’s current condition.

        Patients with bipolar disorder treated with lithium have higher concentrations of NGF in the prefrontal cortex, limbic system, hippocampus, and amygdala.

        Bibliographical references:

        • Aloe, L., Rocco, ML, Balzamino, BO and Micera, A. (2015). Factor nerve growth: a focus on neuroscience and therapy. Current neuropharmacology, 13 (3), 294-303. doi: 10.2174 / 1570159×13666150403231920
        • Freeman RS, Burch RL, Crowder RJ, Lomb DJ, Schoell MC, Straub JA, Xie L. (2004). “NGF Deprivation Induced Gene Expression: After Ten Years, Where Do We Stand?”. Advances in brain research. 146: 111-26. doi: 10.1016 / S0079-6123 (03) 46008-1
        • Sanes DH, Thomas AR, Harris WA (2011). “Natural death of neurons”. Development of the nervous system, third edition. Boston: Academic Press. pages 171-208. ISBN 978-0-12-374539-2
        • Pierucci D, Cicconi S, Bonini P, Ferrelli F, Pastore D, Matteucci C, Marselli L, Marchetti P, Ris F, Halban P, Oberholzer J, Federici M, Cozzolino F, Lauro R, Borboni P, Marlier LN (2001) . “NGF withdrawal induces apoptosis in pancreatic beta cells in vitro.” Diabetology. 44 (10): 1281-95. doi: 10.1007 / s00125010065
        • Ratto MH, Leduc YA, Valderrama XP, van Straaten KE, Delbaere LT, Pierson RA, Adams GP (September 2012). “The Ovulation Inducing Factor Nerve in Semen.” Proceedings of the National Academy of Sciences of the United States of America. 109 (37): 15042-7. doi: 10.1073 / pnas.1206273109

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