Adrenaline is one of the key hormones in the human body. It arose in the process of evolution for a quick response to extreme situations and helps the body to work to the limit. This material is part of the Hormones guide. It belongs to a class of compounds called catecholamines. Adrenaline is primarily produced in the adrenal glands, which are located on top of the kidneys.

The chemical formula of adrenaline is C9H13NO3. Here is a breakdown of the elements and their respective quantities in adrenaline:

  • Carbon (C): 9 atoms
  • Hydrogen (H): 13 atoms
  • Nitrogen (N): 1 atom
  • Oxygen (O): 3 atoms

History of adrenaline research

The history of the discovery of adrenaline was complex. For the most part, it consists of incorrectly conducted experiments, which nonetheless led to major discoveries. Unlike the endocrine glands, some of which were discovered by Galen as early as the 2nd century, people did not know about the existence of the adrenal glands for centuries.

They were discovered only in the 16th century, but the function of the adrenal glands was still unknown until the middle of the 19th century – only then did some ideas about this appear. So, in 1716, a competition was held at the French Academy of Bordeaux on the theme “Quel est l’usage des glandes surrénales?” (“What is the function of the adrenal glands?”). The judge was Charles de Montesquieu (1689–1755). After reading all the writings, Montesquieu decided that none of them deserved an award, and expressed the hope that one day this issue would be resolved.

The conclusion that the adrenal glands are important for the functioning of the body was first made by the British physician Thomas Addison in 1855 based on clinical observations. He worked with patients who experienced severe fatigue, weight loss, vomiting, and strange darkening of the skin. Subsequently, already at the autopsy, he discovered that all of them had damaged adrenal glands. He suggested that it was the destruction of the adrenal glands, whose function was not yet known, that led to the death of these people. About a year later, in France, Charles-Edouard Brown-Séquard attempted to surgically remove the adrenal glands from laboratory animals – they all died, confirming the hypothesis that the adrenal glands are necessary to sustain life.

Neither Addison nor Brown-Séquard knew the actual function of the adrenal glands. It was difficult to imagine that the endocrine glands, including the adrenal glands, release active chemicals into the blood, and besides, it was difficult to demonstrate this with the methods that were available in the second half of the 19th century. In 1889, Brown-Séquard, then a very famous scientist, announced that he had rejuvenated himself by injecting himself with extracts of sperm and testicles of animals – then he was 72 years old. This experiment was set up incorrectly, as these extracts did not contain enough of the male hormone testosterone to have any effect, but Brown-Séquard’s statement made a real sensation. People began to seriously consider the possibility that organ extracts could have physiological effects.

A few years later in England, George Oliver and Edward Sharpay-Schafer discovered that adrenal extracts increased blood pressure in dogs. George Oliver worked as a doctor in a small resort town, and he had a lot of free time for research. In one experiment, he fed his son adrenal glands supplied by a local butcher and tried to measure the effect with a device he had invented to test for possible changes in the thickness of the radial artery. This, too, was not a rigorous scientific experiment: today we know that orally administered epinephrine is not absorbed by the body, and besides, Oliver’s measuring device must have been inaccurate. Nevertheless, this prompted him to continue his research. In London, Oliver met the famous physiology professor Edward Sharpay-Schafer, who, out of sheer interest, administered adrenal extract to dogs and was amazed at how much their blood pressure rose. This was the first unambiguous example of the fact that the secrets of the internal glands have a huge physiological effect.

Immediately after this, a real race began: scientists were the first to seek to find a substance in the adrenal glands that causes an increase in blood pressure. Laboratories all over the world, especially in Germany, England and the USA, raced to isolate it. Some claimed to have found it, but in fact it was received only in 1901. The active substance of the adrenal glands responsible for raising blood pressure was able to isolate Yokichi Takamine, a Japanese immigrant living in the United States. He called it “adrenaline”.

Flight or FIght

Adrenaline is a small molecule that is synthesized in the adrenal medulla. The amino acid tyrosine is taken as the basis, and then several special chemical groups are added to it. The resulting adrenaline is stored in the adrenal glands until it is needed; then it is released into the blood to act on other organs.

The idea of why adrenaline is needed was first formulated by Walter Cannon, a well-known physiologist who worked at Harvard Medical School in the 1910s and 1940s. By that time it was already known that adrenaline affects almost all organs, but it was Walter Cannon who summed up and introduced the concept of the fight-or-flight response. Our ancient ancestors lived in a hostile world, where it was necessary to always be on the alert, quickly respond to possible

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