2023-09-13 16:42:13
Definition: what is noradrenaline (norepinephrine)?
Noradrenaline, also called norepinephrine, is an organic compound produced naturally by the human body but also of synthetic way in the form of drugs.
Noradrenaline is a catecholamine, like dopamine and adrenaline. Like the latter, it acts as a adrenergic hormone and like a neurotransmitter.
It has a preponderant role in cases stress or activity physique. Under these conditions, norepinephrine levels increase in the body, having the effect of preparing the body for a possible escape (in response to stress) or intense effort (in the case of physical activity).
What is the difference between norepinephrine and adrenaline?
Norepinephrine and adrenaline are part of the catecholamine family to which dopamine is added. Noradrenaline is actually a precursor of adrenaline.
THE catecholamines are released into the body in case of stress or physical activity when the sympathetic nervous system is stimulated.
As a reminder, the sympathetic nervous system is the “acceleration pedal” which allows the body to be boosted to respond to stress, danger or physical effort (unlike the parasympathetic nervous system which is the “brake pedal” which puts the body at rest to save energy).
Activation of the sympathetic nervous system leads to increased cardiac output and oxygen transport and elevation of blood sugar. To do this, the nervous system allows a release of noradrenaline at the target organs. There is therefore an activation of the adrenal medulla glands (located at the level of the adrenal glands) which are also a post-synapse of the sympathetic nervous system. The adrenal medulla glands transform dopamine (obtained from the tyrosine) into noradrenaline then norepinephrine into adrenaline.
What is the role of norepinephrine?
An adrenergic hormone
Like the other catecholamines dopamine and adrenaline, norepinephrine has the main role of prepare the body to face adversity. To do this, it activates the alpha and beta adrenergic receptors.
- Alpha 1 receptors are located in the arteries, pupils, liver, digestive tract and salivary glands. Their stimulation by norepinephrine and other catecholamines leads to pupil dilation, contraction of arterial structures, the relaxation of the digestive tract and the stimulation of glycolysis at the hepatic level (which allowsasignificantly increase blood sugar).
- Alpha 2 receptors are located on the arteries, veins and digestive tract. Their stimulation will cause a relaxation of these structures.
- Beta 1 receptors are located mainly on the myocardium. Their stimulation leads an increase in heart rate as well as a optimization of cardiac function (contractility, conduction, excitability, etc.).
- Beta 2 receptors are located on the arteries, veins, bronchi and liver. Their stimulation leads vasodilation (dilation of blood vessels), bronchodilation (dilatation of the bronchi), stimulation of glycolysis (increase in blood sugar).
An important neurotransmitter
Norepinephrine is an important neurotransmitter for attention, wakefulness, sleep, dreaming, sensitivity to emotional signals (fear, pleasure, sexual desire) and learning.
Noradrenaline as a medicine: when and why to use it?
Synthetic norepinephrine essentially stimulates alpha and beta 1 adrenergic receptors. It causes vasoconstriction, a slight increase in the frequency and contractility of the heart. In addition, the administration of noradrenaline allows an increase in blood pressure.
The synthetic norepinephrine is used in certain medical conditions:
- in case of’State of shock : in this case, the norepinephrine produced by the body is no longer sufficient to ensure the arterial transport of oxygen which finds itself in deficit at the cellular level. Synthetic norepinephrine is administered by central or peripheral intravenous infusion.
- in case of’acute hypotension ;
- in the treatment of digestive bleeding (in local gastric irrigation).
We are using more and more drugs with low doses of norepinephrine called “ baby norepinephrine » particularly in the event of hypotension in a preoperative context or secondary to general anesthesia in the elderly or in order to improve blood flow to the brain in the event of seated surgery…
Stress, anxiety, depression: how do you know if you lack norepinephrine?
Certain psychological disorders could indicate that you lack norepinephrine such as:
- and depressed state (sadness, reduced self-esteem, lack of enthusiasm and motivation, absence of desire or pleasure, frequent desire to cry, sleep problems, etc.);
- of the anxiety disorders (generalized anxiety disorder, obsessive-compulsive disorders, etc.);
- problems with concentration and alertness (such as attention deficit disorder with or without hyperactivity or ADHD).
Noradrenergic antidepressants: what indications?
We talk aboutmixed serotonin and norepinephrine reuptake inhibitors. These drugs decrease the presynaptic reuptake of serotonin and norepinephrine, thereby potentiating the effect of these neurotransmitters in the central nervous system. They are indicated in the depression treatment and certain anxiety disorders. Among these drugs we find in particular the milnacipranthe venlafaxine (Effexor®) and la duloxetine.
Excess norepinephrine: why? What effects?
An increase in norepinephrine may indicate a high stress level or a intense physical activity. Additionally, certain illnesses can cause chronic increases in norepinephrine levels. This is the case of phéochromocytome, an adrenal tumor developed at the expense of cells that secrete catecholamines. It causes persistent high blood pressure. Treatment involves surgical removal of the tumor.
In order to diagnose this disease, it is particularly necessary to carry out a dosage of two products of the degradation of norepinephrine (VMA (vanylmandelic acid) and MHPG (3-methoxy-4-hydroxyphenylglycol)) in the blood, urine and urine. cerebrospinal fluid. These tests make it possible to estimate the levels of norepinephrine in the body.
How to stimulate norepinephrine naturally?
It is possible to naturally increase your norepinephrine levels in order to improve your mental well-being and alertness. To do this, make sure to practice regular physical activity.
Additionally, extreme temperatures could increase norepinephrine levels. So the sauna or hammam should be practiced regularly for a better mood (studies on the practice of sauna at 80°C or ice baths indicate that the latter raise norepinephrine levels).
Another tip is toincreasing your protein intake. Indeed, norepinephrine is synthesized from two amino acids, tyrosine and phenylalanine found in the proteins in the food bolus.
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