All About Catecholamines in the Stress Response

Fight-or-Flight Chemical Messengers

Epinephrine or Adrenaline
Epinephrine or Adrenaline - hormone and neurotransmitter. Its IUPAC name is (R)-4-(1-hydroxy- 2-(methylamino)ethyl)benzene-1,2-diol. Cacycle, wikipedia commons

Catecholamines include neurotransmitters such as dopamine, epinephrine (adrenaline) and norepinephrine (noradrenaline), which are released during the body's stress response. They are produced in the adrenal glands, the brainstem, and the brain. They circulate in the blood where they act as hormones and are broken down after just a few minutes. They are then excreted in the urine.

Simple Explanation of Catecholamines and Stress

Catecholamines are an important part of the body's stress response, which can be vital in a fight-or-flight response to a perceived threat.

The adrenaline rush you have probably felt when scared is the result of catecholamines.

They also activate an emotional response in the amygdala of the brain, such as fear of the threat. At the same time, they inhibit areas of the brain involved in short-term memory and concentration while activating the area involved in forming long-term memories. You are ready to fight or flee and you are more likely to remember the threat to react to it in the future.

If activated for too long, catecholamines can produce negative health effects. To counteract these negative effects, it's important to learn to return your body to its prestressed state before the negative effects of prolonged stress can be seen.

Technical Explanation

As the stress response is triggered and the body's sympathetic nervous system (SNS) is activated, the adrenal glands release stress hormones like cortisol, while the sympathetic-adrenomedullary axis (SAM) is also triggered to release catecholamines.

These circulate through the bloodstream and the brain. They act on neuroreceptor sites to create changes in the body to mobilize energy. This is part of "fight or flight," preparing your body to take action.

The immediate effects of catecholamines include: increasing your cardiac output, sending more blood flow to your skeletal muscles, retaining sodium, slowing down the intestines, constricting the blood vessels in the skin, increasing glucose in your bloodstream, opening up your lungs, and making you feel excited.

Your heart is beating faster and directing the flow to your muscles so you'll be able to run or fight. By reducing flow to your skin, there may be less bleeding in case of an injury. You breathe faster and take in more oxygen.

Prolonged exposure to catecholamines can create negative psychological and physical outcomes. Prolonged release of catecholamines can reduce the effects of certain neurotransmitters that affect mood, creating a negative feedback loop between emotions and physiology. These changes can also lead to chronic inflammation of organs and the failure of adaptive systems. This can lead to behavior and quality of life changes, sleep disturbances, metabolic disturbances, and cardiovascular disturbances.

These same catecholamines are part of the body's parasympathetic nervous system (PNS) or the relaxation response. This calms the body's physiology and returns the body to its prestressed state when the perceived threat is gone.

Sources:

How Stress Affects Your Health. American Psychological Association. http://www.apa.org/helpcenter/stress.aspx.

Ranabir S, Reetu K. Stress and Hormones. Indian Journal of Endocrinology and Metabolism. 2011;15(1):18-22. doi:10.4103/2230-8210.77573.

Sherman DK, Bunyan DP, Creswell JD, Jaremka LM. Psychological vulnerability and stress: The effects of self-affirmation on sympathetic nervous system responses to naturalistic stressors. Health Psychology. 2009;28(5):554-562. doi:10.1037/a0014663.

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