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Molecules of Stress

Adrenaline is the name used in most of the world and by general population. In The United States, although most people know it by the same name, the medical profession insists in calling it epinephrine. Doctors call it ‘epi” for short and you probably know what an “epi-pen” is (auto-injector that administers epinephrine.). Adrenaline has Roman roots. Ad + rene (on the kidney) refers to “adrenal” glands which sit on the top of kidneys therefore the hormone produced by them is called adrenaline. Epinephrine has Greek roots. Epi + nephros, again meaning on or over the kidney.


When was it discovered?

In 1895. Napoleon Cybulski, a polish physiologist identified the hormone.


Where does it come from?

Sympathetic nerves have a small supply of it at their nerve endings. At the first sign of stress (demand) they instantly inject it into the recipient organ. The adrenal gland has a large reservoir of adrenaline in its inner part (medulla). On demand, it releases it into the blood stream. Blood flow carries it to the body organs.


How does it work?

All body organ cells have certain molecules called receptors. There are many receptors each only capable of binding with a specific hormone. Adrenaline binds with alpha and beta adrenergic receptors (there are several kinds of alpha and beta receptors depending on the organ). Think of hormones and their receptors as keys and key slots. Only certain keys can enter their couterpart slots to open the lock. The combination of the hormone and the receptor start (unlock) chemical changes in the cells making them behave a certain way.


What does it do?

Every organ reacts differently to adrenaline. Most of the changes occur to help an individual meet the demands of a stressor or cope with danger. It is part of an old and primitive survival physiology.


  • Pupils dilate

  • Heart beats faster and stronger.

  • Small blood vessels constrict.

  • Blood pressure goes up.

  • Breathing becomes faster.

  • Bronchi dilate.

  • Stomach produces more acid.

  • Liver produces more glucose from stored glycogen therefore blood sugar level goes up.

  • Colon activity increases.

  • Bladder contracts.

  • Hands become sweaty.

  • Mouth dries.

  • Blood is diverted from internal organs and skin to the muscles.

  • Cognitive and reasoning functions of brain diminish (blood is diverted to the sensory and motor parts of the brain and away from the cognitive parts).

  • Pain level decreases.

  • Short term memory diminishes.


What happens if adrenaline is taken by mouth?

Nothing! Its half-life is so short it will have no effect whatsoever. As a medication, in can only be used by injection.


What are its medical uses?

Adrenaline is used in several different situations.

  • For severe allergic reactions (anaphylaxis), adrenalin is given either subcutaneously, or in a very dilute concentration, intravenously. Epi-pen is an automatic injector used by the patient to inject it subcutaneously. It reverses broncho-spasm and vasodilatory shock associated with anaphylactic reactions. It could be a lifesaver if applied in time


  • In the intensive care units and operating rooms, it is used to stimulate heart function in patients with failing hearts.


  • During CPR, (cardio-pulmonary resuscitation) it may be used to restore heart function.


  • It is mixed with local anesthetics such as Lidocaine to prolong their action. The local vasoconstriction from adrenaline slows down the absorption of the anesthetic agent.


  • In septic shock, it is used to counteract severe vasodilatation and restore blood pressure.




Cortisol, the molecule which is essential for sustaining life can also hurt you!

It is also known as Hydrocortisone. 


Who discovered it? 

Hench, Kendall and Reichstein were awarded the Nobel Prize in the 1950s for their discovery of cortisol. 


Where does it come from?

The outer part of the adrenal glands, called adrenal cortex, is the body’s factory for manufacturing cortisol. 


What does it do?   

Cortisol, another important hormone of stress, affects body organs in many different ways. Just like adrenaline, it is an important and a very dynamic hormone with certain amounts necessary for basic body functions. The reason its production increases in response to stress is to enable the individual meet the immediate demands of stressors. (fighting, running, surviving an injury etc.). Production of cortisol varies from day to night (diurnal variation) and even from minute to minute according to body’s needs. Lack of enough cortisol (hypocortisolism, adrenal insufficiency) can lead to a variety of illnesses. Chronic excessive production of the hormone is also quite harmful. 


What are its adverse effects?

Chronic elevation of blood cortisol levels (like those caused by chronic stress or prolonged high-dose drug therapy) on various body organs and tissues are as follows:


  • In the liver, cortisol increases production of glucose from amino-acids and glycerol. This increases blood sugar and liver glycogen levels.


  • Cortisol reduces insulin effectiveness further elevating blood sugar levels.


  • In peripheral tissues, cortisol causes protein breakdown in muscle, bone, connective tissue and skin. Therefore, chronic elevation of blood cortisol levels cause muscle atrophy and weakness, osteoporosis, frail and weak tissues, thin skin and thin capillaries that break easily (excessive bruising) . People who take synthetic cortico-steroids (drugs that work similar to cortisol) notice these effects as well.


  • Cortisol reduces availability of Calcium for bone mineralization and increases bone re-absorption, further aggravating osteoporosis.


  • Chronic excessive cortisol results in increased distribution of fat in the abdomen, face, neck and back and loss of fat in the arms and legs. This can lead to higher levels of “bad” cholesterol and lower levels of “good” cholesterol increasing the risk of heart attacks and strokes.


  • Cortisol enhances the vascular reactivity to substances that increase blood pressure, therefore it can cause hypertension.


  • Cortisol affects mood and behavior. Excessive levels cause apathy, depression, insomnia, reduced memory and even psychosis. It can also impair cognitive functions.


  • By a variety of mechanisms, cortisol diminishes inflammatory and immune responses. Because of this activity, cortico-steroids are used as strong anti-inflammatory agents. However, by reducing immune functions, cortisol and similar drugs increase the risk of infections and cancers.



What are some of the therapeutic uses of cortisol-like drugs such as cortisone, hydrocortisone, prednisone, prednisolone, methyl-prednisolone and dexamethasone?

  • Inflammatory conditions such as rheumatoid arthritis, lupus, vasculitis, myositis, asthma and skin erruptions.

  • Anti-rejection therapy after organ transplants.

  • Adrenal insufficiency.

  • Nephrotic syndrome.

  • Increased intracranial pressure (brain swelling).

  • Severe COPD (chronic obstructive pulmonary disease).

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