Catecholamines are a group of compounds that have a structural similarity to tyrosine. These include neurotransmitters and hormones. For this reason, catecholamines are extremely important for the internal regulation of the body and the functioning of the nervous system. Which compounds belong to catecholamines? What is their role in the human body?
Contents:
- Catecholamines - effect on the body
- Catecholamines as neurotransmitters
- Catecholamines as hormones
- Catecholamines as drugs
- Catecholamines - breakdown of catecholamines in the human body
- Causes of high levels of catecholamines in the body
Catecholaminesoccurring in the human body are primarily neurotransmitters, i.e. substances responsible for transmitting information between nerve cells. They have a monoamine structure and the fact that they are formed in the body from tyrosine, i.e. one of the amino acids. Catecholamines cannot be supplied with food. Our body must synthesize them on its own from protein nutrients.
The most important substances belonging to catecholamines are:
- adrenalina
- noradrenalina
- dopamine
These compounds are mainly produced by the cells of the adrenal medulla and the postganglionic fibers of the sympathetic nervous system.
Dopamine is an active neurotransmitter in the central nervous system. Due to the localization of its action, it is largely synthesized within the brain stem.
Catecholamines are water-soluble chemicals. They can be transported in the blood dissolved in plasma or bound to proteins. Thanks to this, adrenaline can reach various organs of the body performing a hormonal function.
Many stimulants are analogues of catecholamines. This group includes amphetamine derivatives.
Catecholamines - effect on the body
The level of catecholamines in the body increases in stressful situations. These substances are responsible for triggering the "fight or flight" reaction. Under their influence, the body prepares itself for intense physical exertion in response to a stress stimulus.
This mechanism evolved in our ancestors, who had to hunt and fight for survival.
The increase in catecholamines concentration may be caused by psychological situations or stressorsenvironmental conditions such as increased sound levels or intense light.
The increase in catecholamines concentration in the body is caused by:
- increase in blood pressure
- heart rate acceleration
- raise blood glucose
Catecholamines as neurotransmitters
Norepinephrine and dopamine are catecholamines that act as neurotransmitters in the central nervous system. This means that they are chemicals released by neurons to send signals to other nerve cells.
Dopamine is active in the brain where it performs several different functions. One of them is the role of the reward center stimulant. In this way, it participates in the motivation mechanism that guides our behavior.
Many addictive substances stimulate the release of dopamine in the brain, thereby stimulating the reward center. Drugs and some medications are such compounds. This mechanism is involved in the development of addiction.
Another role for dopamine is to participate in the neurotransmission responsible for the motor control of the body.
During Parkinson's disease, a decrease in the concentration of this neurotransmitter within the substantia nigra of the brain is observed. A dopamine deficiency in this disorder results in muscle stiffness and tremors.
In popular culture and the media, dopamine is often described as the chemical responsible for experiencing pleasure. From the point of view of science, however, this substance is primarily motivating.
This means it drives the body's behaviors that bring it closer to its goal. Dopamine is responsible for the pleasant feeling of satisfaction with success.
Norepinephrine is a neurotransmitter responsible for mobilizing the brain and body to act. Its release from nerve fibers is low during sleep.
The highest concentration of this substance occurs in stressful or emergency situations. In the brain, norepinephrine works by causing excitation and increasing alertness. It has a positive effect on memory and concentration. At the same time, it is responsible for anxiety reactions.
Noradrenaline in the nervous system also acts peripherally, i.e. on the whole body, not only on the mind and psyche. Its increased concentration increases heart rate, blood pressure and stimulates the release of glucose into the bloodstream.
In addition, it increases blood flow to skeletal muscles while reducing blood supply to the digestive system. This action is to prepare the body to fight or flee.
Catecholamines as hormones
Adrenaline, also known as epinephrine,acts as a hormone in the body. This means that it is a compound produced by the body and then released into the blood. Hormones travel through the bloodstream to various tissues.
Adrenaline, hitting the blood into the cells of the body, causes metabolic changes in them. This leads to effects such as increased heart performance, dilated pupils, and increased sugar transport to the body's organs.
It also stimulates blood flow through the muscles. The mechanism of action of this hormone is based on the binding of its molecules with alpha and beta receptors on the surface of cell membranes.
Adrenaline is usually produced by both the adrenal glands and a small number of neurons in the medulla of the brain. In the nervous system, it can also act as a neurotransmitter, like noradrenaline and dopamine.
In this way of signaling, it is involved in the regulation of visceral functions. It regulates, among other things, breathing.
This catecholamine was first isolated by a Polish scientist, Napoleon Cybulski in 1895.
Catecholamines as drugs
Catecholamine used in medicine as a drug, among the previously mentioned, is only adrenaline. It is used primarily in cardiac arrest situations. Injection of this substance:
- stimulates the contractility of the heart muscle
- improves the conductivity of stimuli in the heart
- increases the effectiveness of electric defibrillation
Adrenaline is used in cases of anaphylactic shock, cardiac arrest and cardiogenic shock.
It is sometimes used to stop superficial bleeding because it constricts the blood vessels locally. It can also be used in asthma when other treatments have not worked.
This catecholamine is administered intravenously, by injection into the muscle, by inhalation or by subcutaneous administration. Common side effects of adrenaline include tremors, restlessness and sweating. You may also experience increased heart rate and high blood pressure.
The structure of the catecholamine is also found in the drug levodopa. It is a substance that is a dopamine precursor. This drug is used in the treatment of Parkinson's disease.
The therapeutic mechanism of this catecholamine is that when it crosses the blood-brain barrier, it is converted into dopamine. As a result, it increases the concentration of this neurotransmitter in the substantia nigra of the brain, reducing the symptoms of the disease.
Another drug that belongs to catecholamines is isoprenaline. It's a synthetic derivative of adrenaline, nooccurring naturally in the body.
This substance is used to treat bradycardia (slow heart beat), heart block, and rarely in asthma.
Catecholamines - breakdown of catecholamines in the human body
The half-life of catecholamines in the human bloodstream is several minutes. Its decomposition is caused by methylation processes with the use of catechol-O-methyltransferases (COMT) or deamination with monoamine oxidases (MAO).
There are drugs used in medicine that base their therapeutic effect on blocking monoamine oxidases (MAO). The group of these substances is known as MAO inhibitors. They are used as drugs that increase the concentration of neurotransmitters in the brain in people with depression.
Their second application is to increase the effectiveness of Parkinson's disease therapy with the use of levodopa. In this way, they block the breakdown of this drug in the bloodstream.
Causes of high levels of catecholamines in the body
In our body, apart from the moments of their increased release, related to e.g. stress, the level of catecholamines in the blood is low. Consistently high levels of catecholamines may be associated with the presence of tumors of the types that increase their production.
Significantly elevated catecholamine levels may be caused by neuroendocrine tumors in the adrenal medulla. The increase in the concentration of these substances is also observed in the case of other changes:
- pheochromocytoma (phaeochromocytoma)
- neuroblastoma
- zwojaka (ganglioneuroma)
Another cause of high catecholamines levels may be Brunner's syndrome, which is monoamine oxidase A (MAO-A) deficiency. It is the enzyme responsible for breaking down these substances in the body. Therefore, its lack significantly increases the amount of these neurotransmitters in the blood.
About the author
Sara Janowska, MA in pharmacyPhD student of interdisciplinary doctoral studies in the field of pharmaceutical and biomedical sciences at the Medical University of Lublin and the Institute of Biotechnology in Białystok. A graduate of pharmaceutical studies at the Medical University of Lublin with a specialization in Plant Medicine. She obtained a master's degree defending a thesis in the field of pharmaceutical botany on the antioxidant properties of extracts obtained from twenty species of mosses. Currently, in his research work, he deals with the synthesis of new anti-cancer substances and the study of their properties on cancer cell lines. For two years she worked as a master of pharmacy in an open pharmacy.
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