What is norepinephrine?
Norepinephrine, also called noradrenaline, is both a neurotransmitter and a hormone. As a neurotransmitter, it’s a chemical messenger that helps transmit nerve signals across nerve endings to another nerve cell, muscle cell or gland cell. As a hormone, it’s released by your adrenal glands, which are hat-shaped glands that sit on top of each kidney.
As a neurotransmitter, norepinephrine is made from dopamine. Norepinephrine is made from nerve cells in the brainstem area of your brain and in an area near your spinal cord.
Norepinephrine is part of your sympathetic nervous system, which is part of your body’s emergency response system to danger — the “fight-or-flight” response. Medically, the flight-or-flight response is known as the acute stress response.
What does norepinephrine do in the body?
As a neurotransmitter in your brain and spinal cord, norepinephrine:
- Increases alertness, arousal and attention.
- Constricts blood vessels, which helps maintain blood pressure in times of stress.
- Affects your sleep-wake cycle, mood and memory.
What triggers norepinephrine release?
As a hormone, stress triggers the release of norepinephrine from your adrenal glands. This reaction causes a number of changes in your body and is known as the fight-or-flight response.
What’s the fight-or-flight response?
The fight-or-flight response refers to your body’s response to a stressful situation, such as needing to escape danger (moving away from a growling dog) or facing a fear (giving a speech for school or work). The term comes from the choice our ancestors faced when confronted with a dangerous situation — to stay and fight or run to safety.
During the fight-or-flight response, you (your brain) perceive danger. Next, nerves in an area of your brain called the hypothalamus send a signal down your spinal cord, then out to your body. The neurotransmitter that transmits your brain’s nervous system message of what to do is norepinephrine (noradrenaline). The neurotransmitter noradrenaline reaches the following organs and tissues and causes these rapid body reactions:
- Eyes: Pupils dilate to let more light in to better see more of your surroundings.
- Skin: Skin turns pale as blood vessels receive a signal to divert blood to areas more in need of your blood’s oxygen, such as your muscles, so you can fight or run away.
- Heart: Heart pumps harder and faster to deliver more oxygenated blood to areas most in need, like your muscles. Blood pressure also increases.
- Muscles: Muscles receive more blood flow and oxygen so they can react with greater strength and speed.
- Liver: Stored glycogen in your liver is converted to glucose to provide more energy.
- Airways: Breathing is deeper and faster. Your airways open up so more oxygen is delivered to your blood, which goes to your muscles.
The neurotransmitter noradrenaline also reaches your adrenal gland, which releases the hormones adrenaline (epinephrine) and noradrenaline (norepinephrine). These hormones travel through your blood to all parts of your body. They reach your eyes, heart, airways, blood vessels in your skin and your adrenal gland again. The “message” to these organs and tissues is to continue to react until you’re out of danger.
This is a simple description of the fight-or-flight response. Other parts of your nervous system are also involved, as well as other organ systems, hormones and neurotransmitters.
How is norepinephrine used as a medication?
When used as medicine, norepinephrine is used to increase and maintain blood pressure in limited, short-term situations where low blood pressure is a problem. These conditions could include:
- Cardiac arrest.
- Spinal anesthesia.
- Blood transfusions.
- Drug reactions.
Norepinephrine is usually used with other medicines for the conditions mentioned above.
Norepinephrine is also used to treat:
- Septic shock, a life-threatening condition resulting in extremely low blood pressure following an infection.
- Neurogenic shock, a life-threatening condition caused by injury to your spinal cord.
- Pericardial tamponade, a condition in which extra fluid builds up in the space around your heart.
- Critical hypotension.
What are the side effects of norepinephrine as a medication?
Side effects of norepinephrine as an injection that require medical attention include:
- Allergic reactions like skin rash, itching or hives, swelling of your face, lips or tongue.
- Difficulty breathing, wheezing.
- Irregular heartbeats, palpitations or chest pain.
- Pain, redness or irritation at site where injected.
What health conditions result from low levels of norepinephrine?
Health conditions that result from low levels of norepinephrine include:
- Attention deficit hyperactivity disorder (ADHD).
- Memory problems.
- Sleeping problems.
- Low blood pressure (hypotension)
- Low blood sugar (hypoglycemia).
- Changes in blood pressure, heart rate.
- Dopamine beta-hydroxylase deficiency. This rare genetic disease prevents your body from converting dopamine into norepinephrine.
What health conditions result from high levels of norepinephrine?
Health conditions that result from high levels of epinephrine include:
- High blood pressure (hypertension).
- Rapid or irregular heartbeat.
- Excessive sweating.
- Cold or pale skin.
- Severe headaches.
- Nervous feeling, jitters.
- Pheochromocytoma, which is an adrenal gland tumor.
People with high norepinephrine levels have a greater risk of heart, blood vessel and kidney damage.
What can I do to boost my norepinephrine levels naturally?
You can increase your levels of norepinephrine naturally by:
- Exercising regularly (30 minutes a day at least five days a week).
- Getting an adequate amount of sleep (try to get seven to nine hours a night).
- Eating meats, chicken, fish, nuts, eggs and cheese.
- Listening to music or doing something that brings you joy (feeling happy increases the release of norepinephrine).
What are the similarities and differences between epinephrine and norepinephrine?
|Epinephrine (adrenaline)||Norepinephrine (noradrenaline)|
|Neurotransmitter (NT)||Yes||Yes, it’s the most common NT of your sympathetic nervous system; mainly works as an NT|
|Hormone||Yes, mainly works as a hormone||Yes|
|Part of fight-or-flight response||Yes||Yes|
|Made in/released from||Mainly in and from your adrenal glands||Mainly in and from your nerves|
|Works on/action||Acts on almost all body tissues||Mainly works to increase or maintain blood pressure|
|When released into bloodstream||During times of stress||Continuously|
|Common use in medicine||Severe asthma, anaphylaxis, low blood pressure from severe conditions||Emergency low blood pressure conditions|
A note from Cleveland Clinic
Norepinephrine is both a neurotransmitter and a hormone, but it acts mainly as a neurotransmitter. Norepinephrine, also known as noradrenaline, plays an important role in your body’s fight-or-flight response. As a medication, norepinephrine is used to increase and maintain blood pressure in limited, short-term serious health situations.
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