What Is Norepinephrine?

A chemical/hormone that affects mood, energy, and more

Norepinephrine is both a chemical messenger from your central nervous system (CNS) and a stress hormone released from within your adrenal glands. It regulates numerous internal functions that keep your brain and body running efficiently.

This article explains the many important functions of norepinephrine, or NE. It also includes information about the causes of abnormal norepinephrine levels and related conditions, along with ways you can keep your NE levels balanced.

MRI of the brain

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Where Norepinephrine Is Generated

Your brain and spinal cord make up your CNS. This is your body's main processing hub, so to speak—where external and internal information gets interpreted. It controls a host of things, including your routine movements, bodily functions, senses, thoughts, hunger levels, and more.

The CNS is able to communicate with your body because of nerve cells called neurons. You have around 86 billion of them, and their job is to transmit signals from your brain to your muscles and cells—why they are also called chemical messengers or neurotransmitters.

Specialized neurons located within your brainstem and spinal cord, called postganglionic neurons, are among them. These are the neurons that release norepinephrine.

Once released, NE travels to its target nerve, binds to the nerve's receptor, and directs it take an action. That directive might be go to sleep or wake up, be more focused, feel happy, and much more.

Norepinephrine is also produced in the inner part of your adrenal glands called the adrenal medulla. In this case, NE is generated because of the sympathetic nervous system (SNS)—the driving force behind your fight-or-flight response.

When the body senses stress, your SNS signals your adrenal glands to release norepinephrine. NE then travels through your bloodstream and, as a hormone, initiates a stress response that allows you to quickly mobilize your body and brain so you can protect yourself.

What Norepinephrine Does

Norepinephrine is at the center of a variety of functions that help keep you healthy. Sometimes, you may be well aware that it's coursing through your veins; think of sweaty palms when you're nervous or a racing heartbeat when you're scared. Other times, you may have no idea it's even there.

Here's a look at what norepinephrine does for you.

Keeps Your Biorhythms Steady

Biorhythms are body cycles involved in your physical, emotional, and intellectual health. Low amounts of norepinephrine are always circulating in your system to keep these cycles stable.

Biorhythms that NE helps regulate include:

  • Blood flow to your skeletal muscles
  • Skeletal muscle contraction, which enables you to move
  • Glucose levels in your bloodstream
  • Mood stability

Maintains Organ Function

All together, NE affects numerous organs throughout your body, including:

  • Eyes: NE increases tear production and dilates the pupils in response to light and emotion.
  • Kidneys: NE triggers your kidneys to release renin, which regulates salt and water balance.
  • Pancreas: NE triggers your pancreas to release glucagon so that your liver can produce more glucose.
  • Lymphoid organs: NE stimulates such organs as your spleen, thymus, and lymph nodes to help your immune system fight infection.
  • Intestines: NE decreases blood flow to your intestines and slows down your digestive system.

Protects You From Harm

Norepinephrine enables your stress response to protect you from danger, whether actual or perceived.

Take being exposed to extreme cold, for example. Your body knows that most of its heat is lost through your skin. To keep you well, you need to conserve whatever warmth you have.

To do that, your nerves release norepinephrine, which then binds to cell receptors in your skin. Because NE narrows blood vessels, it reduces blood flow to the skin, making heat less able to escape.

Other types of threats trigger a different response. When your brain perceives an external threat like someone chasing you, for example, part of the brain known as the hypothalamus excites your SNS. This triggers your adrenal glands to pump norepinephrine.

As part of this response, norepinephrine increases:

  • Alertness
  • Focus
  • Pain tolerance
  • Reaction time
  • Breathing rate
  • Memory retrieval

Digestion and the immune system are treated as non-essential functions during this period. NE shuts them down so that more energy can go to the functions needed to keep you safe.

Together with adrenaline, norepinephrine also raises your heart rate and blood pressure, and stimulates your liver to produce more blood sugar (glucose) so that your body can use it for energy.

A similar reaction can occur in situations that simply make you feel nervous or stressed, but that aren't true threats (e.g., a tense work meeting or an argument with a partner).

Recap

Low amounts of norepinephrine continuously move through your central nervous system to regulate your basic bodily functions. When faced with stress or danger, your hypothalamus alerts your brain to pump out more norepinephrine to gear you up for action.

Norepinephrine-Related Conditions

Healthcare providers don't typically test norepinephrine levels during routine check-ups. They may suspect a change in your NE levels based on your symptoms, though, in which case they may order a urine or blood test to investigate.

The normal norepinephrine range for a blood test is between 70 and 1700 picograms per millilitre (pg/mL). There are numerous explanations for why your NE levels could be higher or lower than that, from rare tumors to anxiety and stress.

The cause of the change in your NE levels may not be immediately clear to your healthcare provider. In that case, they will need to investigate further by performing more tests based on your symptoms.

Low Norepinephrine Activity

Low norepinephrine levels are a hallmark of several major conditions, including:

Each of these conditions has its own distinct profile of symptoms. That said, they also have several symptoms in common, many of which point to low norepinephrine.

These include:

High Norepinephrine Activity

A somewhat high NE activity level makes you happy, and a really high level makes you euphoric. Many recreational drugs get people "high" by increasing levels of norepinephrine and another neurotransmitter, dopamine.

Conditions associated with having elevated NE levels include:

  • Anxiety disorders
  • Pheochromocytoma, a tumor on the adrenal glands
  • Chronic stress
  • The manic phase of bipolar disorder

Like conditions related to low norepinephrine, those related to high NE have both unique and shared symptoms as well.

Symptoms that overlap and point to high norepinephrine levels include:

Paroxysmal sympathetic hyperactivity (PSH) is a term that describes a group of symptoms related to being "stuck" in fight-or-flight mode—a possible outcome of too-high norepinephrine.

One of the most common causes of PSH is traumatic brain injury, but it has also been linked to stroke, spinal cord injury, and inflammation in the brain (encephalitis).

Symptoms of paroxysmal sympathetic hyperactivity include:

Recap

Having too much or too little NE can cause symptoms that are common across many health conditions. If you are experiencing mood swings, anxiety, headaches, fatigue, or other NE-related symptoms, your healthcare provider may order a urine or blood test to measure your norepinephrine levels.

Treatment

A change in your norepinephrine levels can contribute to the conditions described above or happen as a result of them. But rather than treating the norepinephrine imbalance itself, healthcare providers treat the related condition and monitor how their patient's symptoms respond.

Depending on your condition, your healthcare provider may prescribe a medication that affects norepinephrine activity.

Norepinephrine Antagonists

Norepinephrine antagonists are drugs that lower blood pressure and heart rate by suppressing norepinephrine activity. They are often used to treat high blood pressure, congestive heart failure, heart rhythm problems, and angina (chest pain that occurs when there is not enough blood flow to the heart).

Norepinephrine antagonists exert a number of effects that are useful for treating other conditions in which norepinephrine levels are high as well. Though they are not approved by the U.S. Food and Drug Administration (FDA) for these purposes, norepinephrine antagonists may be used off-label for ADHD, insomnia, post-traumatic stress disorder (PTSD), anxiety disorders, and more.

Commonly prescribed norepinephrine antagonists include:

Beta-Blockers

Beta-blockers work by blocking norepinephrine from binding to receptors in your sympathetic nervous system. In doing so, they relax your heart and lower your blood pressure.

Beta-blockers have traditionally been used used to treat high blood pressure and angina. They may also be prescribed off-label to treat anxiety disorders and related symptoms, including migraines and nightmares, or to prevent PTSD after a traumatic event.

Commonly prescribed beta-blockers include:

  • Sectral (acebutolol)
  • Levatol (penbutolol)
  • Inderal (propranolol)

Serotonin-Norepinephrine Reuptake Inhibitors

Serotonin and norepinephrine reuptake inhibitors (SNRIs) are medications that are used to treat anxiety and depression, but they can also be used to treat panic disorders, ADHD, obsessive-compulsive disorder, and more.

SNRIs increase norepinephrine activity by preventing NE from being reabsorbed into nerve cells. These drugs are effective for improving mood, energy, and attentiveness along with other symptoms related to having low norepinephrine levels.

Commonly prescribed SNRIs include:

Amphetamines

Amphetamines increase norepinephrine activity by stimulating its release and preventing it from reabsorbing into nerve cells.

These drugs are considered a first-choice treatment for ADHD, because they increase concentration and reduce impulsivity. This makes it easier for people with ADHD to complete tasks and meet goals.

Commonly prescribed amphetamines include:

  • Adderall (dextroamphetamine)
  • Ritalin (methylphenidate)

Recap

Norepinephrine antagonists and beta-blockers reduce norepinephrine activity and are helpful for treating depression, anxiety, and panic disorders. SNRIs and amphetamines increase norepinephrine activity and are helpful for improving mood, energy, and focus.

Natural Ways to Boost Norepinephrine

Keep in mind that norepinephrine is part of your body's response to stress. Thus, one of the best ways to keep your NE levels balanced is to reduce physical and emotional stress in your life.

People with mild norepinephrine deficiency may be able to improve their symptoms by making healthy lifestyle changes, specifically:

  • Exercising regularly
  • Getting enough sleep
  • Setting and meeting goals
  • Enjoying music or making art
  • Meditating
  • Eating a healthy, well-balanced diet

If you are experiencing depression, anxiety, PTSD, or another disorder that is affecting your quality of life, these methods can help, but may not be sufficient enough to treat your condition. Speak to your healthcare provider.

Norepinephrine Use in Medicine

A drug form of norepinephrine called Levophed is used in the ER to raise blood pressure that drops dangerously low (acute hypotension) due to complications from surgery or medical conditions.

Levophed is often given when a patient goes into cardiac arrest to restore blood flow. It is also commonly used to correct hypotension in people being treated for sepsis, a condition in which the body responds to infection by attacking its own tissues.

Levophed is given through an IV into your vein. Possible side effects of the drug include:

  • Slow, uneven heart rate
  • Reduced urination
  • Trouble breathing
  • Changes in vision, speech, or balance
  • Severe headache

Summary

Norepinephrine is a hormone and a neurotransmitter that affects numerous aspects of your mental, emotional, and physical health. Low levels of norepinephrine are continuously at-work in your brain and body, but levels increase when you are faced with stress, danger, or another threat.

If you are experiencing symptoms that could be related to norepinephrine, your healthcare provider may order tests to measure how much NE is in your system. If treatment is needed, it will be focused on the related condition. Prescription medications that balance norepinephrine may help improve your symptoms.

A Word From Verywell

Trauma and chronic stress can cause your hormones and neurotransmitters to become imbalanced. Ultimately, this can have a serious impact on your health and overall wellbeing.

If you are dealing with trauma or chronic stress, or if you simply need someone to talk to, let your healthcare provider know. It's every bit as important to protect your mental health as it is to protect your physical health.

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