Blood & Laboratory Values

Eicosanoids – Function & Diseases

Eicosanoids

Eicosanoids are hormone-like hydrophobic substances that act as neurotransmitters or immune modulators. They are formed as part of fat metabolism . Raw materials are omega-6 and omega-3 fatty acids .

What are eicosanoids?

The hormone-like eicosanoids play a major role as neurotransmitters or immune modulators. Sometimes they evoke opposite reactions. Basically, they are mediators between the immune system and the nervous system. The eicosanoids are derived from omega-6 or omega-3 fatty acids.

They contain 20 carbon atoms, which is where their name comes from. In Greek, the word twenty means “eikosi”. All eicosanoids contain prostanoic acid as their basic structure. There are three series of eicosanoids. Series 1 is synthesized from dihomogammalinolenic acid (DGLA) and has anti-inflammatory properties. Therefore, the active ingredients in this series are often referred to as the good eicosanoids. Series 2 with the so-called evil eicosanoids is responsible for inflammatory reactions and pain conduction. It is made from arachidonic acid (AA).

Series 3 is derived from eicosapentaenoic acid (EPA). This series also has an anti-inflammatory effect and is the antagonist of series 2. The groups of substances resulting from these series act via G-protein-coupled membrane receptors. The individual substance groups can be divided into prostaglandins, prostacyclin , thromboxanes and leukotrienes . Series 2 proves to be the most important series of eicosanoids, although it contains substances that promote inflammation. However, these are defense reactions of the body that are necessary in the acute situation.

Function, effect & tasks

The eicosanoids represent a variety of hormone-like active substances that perform different functions for the organism. In general, these are substances that mediate between the immune system and the nervous system . 

In the case of infections, injuries, trauma or the effects of foreign particles, some of the eicosanoids stimulate defense reactions that manifest themselves in inflammation and pain. Opponents of these substances, which belong to the same substance class, also have an anti-inflammatory effect. Both functions are vital for the body. Dihomogammalinolenic acid (DGLA) is the starting material responsible for series 1. This compound is a precursor to anti-inflammatory series 1 eicosanoids. However, it is also a precursor to arachidonic acid, which in turn acts as a precursor to series 2 eicosanoids.

Arachidonic acid is always associated with the synthesis of pro-inflammatory eicosanoids. In reality, as part of the arachidonic acid metabolism, metabolites with sometimes very contradictory functions are formed. So there are pro-inflammatory and fever-increasing as well as anti-inflammatory and fever-reducing metabolites. The series 3 eicosanoids are anti-inflammatory and act as a real antagonist to series 2. Their starting material is eicosapentaenoic acid and, in contrast to the other series, an omega-3 fatty acid. Most eicosanoids are also so-called prostaglandins. They are almost congruent with the three series.

So there are both pro-inflammatory and anti-inflammatory prostaglandins. By far the most important role is played by the prostaglandins of series 2. They are responsible for pain, inflammation and blood clotting and are therefore a special target of the pharmaceutical industry. Various drugs are being tested to limit their effects. Series 2 prostaglandins also include prostacyclin and thromboxane.

Prostacyclin is involved in the inflammatory response. At the same time, however, it counteracts blood clotting. Thromboxane is the antagonist of prostacyclin in terms of blood clotting. It activates platelet aggregation. The leukotriene group of substances also belongs to the eicosanoids. The leukotrienes are not prostaglandins. But they are also derived from arachidonic acid. They are found in the white blood cells and also promote inflammatory processes.

Formation, Occurrence, Properties & Optimal Values

The eicosanoids are derived from unsaturated fatty acids . It is mainly the omega-6 and omega-3 fatty acids that play a role. For the eicosanoids of series 1 and 2, gamma-linolenic acid serves as the starting material.

It is an omega-6 fatty acid synthesized from the essential linoleic acid or ingested via vegetable oils. Dihomogammalinolenic acid and arachidonic acid are formed from linoleic acid and finally gamma-linolenic acid. However, arachidonic acid is also supplied through food independently of biosynthesis. Finally, linoleic acid is the starting material for both anti-inflammatory and pro-inflammatory eicosanoids. Gamma-linolenic acid is particularly found in borage oil, evening primrose oil and hemp oil.

Its starting material (linoleic acid) can be found in many vegetable oils such as sunflower oil, rapeseed oil or olive oil. The omega-3 fatty acid eicosapentaenoic acid is the starting material for the anti-inflammatory series 3 eicosanoids, which are also antagonists to series 2. Eicosapentaenoic acid is mainly found in fish oil. Salmon and herring in particular are rich in eicosapentaenoic acid.

Diseases & Disorders

All eicosanoids perform extremely important functions in the body. The inflammatory reactions caused by various prostaglandins are also vital for physical defense reactions.

However, these prostaglandins are also active in allergic reactions and autoimmune diseases . In this case, the immune reaction is directed against normally harmless foreign proteins or, in the case of autoimmune diseases, even against the body’s own proteins . Which processes lead to these incorrect reactions has not yet been fully elucidated. However, the enhanced effects of Series 2 eicosanoids can also lead to this. To prevent this, there must be a balance between omega-6 and omega-3 fatty acids in the diet.

Sufficient amounts of omega-6 fatty acids are ingested with food today. However, there is often a deficit of omega-3 fatty acids, since these can mainly be obtained from fish oil today. However, diseases such as diabetes mellitus , obesity , stress , liver disease, physical inactivity or vitamin and mineral deficiencies can also affect the body’s metabolic processes in such a way that an imbalance between omega-6 and omega-3 fatty acids occurs. The consequences are increased inflammatory reactions and the increased occurrence of allergies , asthmatic symptoms and autoimmune diseases.

Lisa Newlon
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Hello! I am Lisa Newlon, and I am a medical writer and researcher with over 10 years of experience in the healthcare industry. I have a Master’s degree in Medicine, and my deep understanding of medical terminology, practices, and procedures has made me a trusted source of information in the medical world.