Nitric Oxide (neurotransmitter): Definition And Functions
Some of you probably think that nitric oxide is a laughing gas, better known as “laughing gas.” Well, that is nitrous oxide (N2O).
In this article we will talk about nitric oxide, also called nitrogen monoxide or NO (for its acronym in English), is a fat-soluble gas molecule that acts as a neurotransmitter in the brain and carries out different functions within our body.
Since its discovery, nitric oxide has become one of the most studied molecules in human physiology. Studies confirm the natural ability of nitric oxide to prevent clotting, regulate inflammation, revitalize tissues, improve erectile dysfunction or kill invading microorganisms and even eradicate cancer cells.
In addition, nitric oxide promotes erection, and as a supplement it is consumed in sports training and bodybuilding circuits, as it promotes resistance to fatigue and improves muscle development.
And this gas has aroused great scientific interest. Already in 1970, an American doctor named Ferid Murad realized that nitrates used when people suffer from chest pain or cardiovascular problems release nitric oxide, since This substance has a dilating effect on blood vessels and relaxes the muscle layer in the endothelia
A few years later, in 1987, studies confirmed that the human body produces nitric oxide, which led to research into how it is formed, what it does and what the functions of this compound are within the human body. In 1998, the authors of these discoveries, Robert Furchgott, Ferid Murad and Louis J. Ignarro, received the Nobel Prize.
Nitric oxide is synthesized from the protein amino acid arginine and L-citrulline , a non-protein amino acid, thanks to the action of an enzyme called nitric oxide synthase (NOS). Furthermore, for the synthesis to occur, the presence of oxygen and a coenzyme (an organic molecule that binds to the enzyme) is necessary. reduced nad-phosphate (NADPH). In most living beings, NO is produced in different types of cells.
Functions in our body
In addition to the studies that I mentioned before and that earned their authors the Nobel Prize, in the last three decades there have been more than 60,000 investigations carried out on this gas.
Nitric oxide plays different roles in both the central and peripheral nervous systems among which stand out:
Nitric oxide as a neurotransmitter
Neurotransmitters are chemical molecules that send signals within the nervous system. Nitric oxide, being a gas, does not fit the classic definition of other neurotransmitters such as dopamine or serotonin.
However, This gas molecule performs functions as a neurotransmitter and neuromodulator
According to the authors Fernández-Álvarez and Abudara Morales, neurotransmitters, classically, should meet these requirements:
Should be present at the presynapse
It should be stored in the presynaptic terminal
Should be released upon presynaptic nerve stimulation
Exogenous administration of the substance would cause a response identical to that caused by presynaptic nerve stimulation and the drugs must cause the same modifications in the response caused by presynaptic nerve stimulation.
In the synapse there must be mechanisms that allow the action of said neurotransmitter substance on the postsynaptic neuron to end.
Since NO is a gas and its physical-chemical functions are different from other neurotransmitters, it does not meet all of the criteria set out above. However, This does not mean that it does not act as a chemical messenger but this type of transmission constitutes a particular form of transmission.
Generally, neurotransmitters are produced, stored and used when the nervous system requires them. Once these are used, an enzyme acts on them, often degrading them. In the case of NO this does not happen, since it does not occur in advance. It is synthesized when it is needed.
Furthermore, unlike other neurotransmitters, it does not have a localized effect, but rather diffuses in many directions and, being a gas, can affect many cells. Therefore, although both classical neurotransmitters and NO send information, they do so in a different way.
Nitric oxide and its relationship with Viagra
Research on this gaseous compound has also concluded that nitric oxide is of utmost importance in male erection In fact, the medications used to treat erectile dysfunction act on the nitric oxide pathway that allows blood flow to the male organ.
One of the best-known medications to treat this problem is Sildenafil, which you probably know by its trade name: “Viagra.” But what is the relationship between Viagra and nitric oxide? Well, when we think about having intimate relations with someone or we are in a situation in which intimate stimulation occurs, nitric oxide is released in the nerve endings of the male organ
This compound causes relaxation of the muscles, dilation of the corpora cavernosa and blood vessels in this area, and this relaxation allows blood to enter the arteries and, consequently, an erection. When nitric oxide is mobilized towards the smooth muscle cells present in the blood vessels, it causes different chemical reactions by increasing the chemical messenger cGMP, this produces the dilation of the vessels that allows blood flow. Once cGMP has performed its function, it is degraded by the enzyme phosphodiesterase (PDE). Viagra blocks phosphodiesterase, thus preventing the degradation of cGMP and improving erection.
