Melanin is a pigment that is responsible, among other things, for the color of our skin, hair or the irises of our eyes and protects against harmful UV radiation. But why do some people have more melanin and others less? What are other functions of melanin and are there any diseases in which these pigments are abnormal?

Melaninis a pigment that is responsible for the color of our skin, hair and eyes. The name of the dyes in this group comes from the Greek word " molasses " which can be translated as dark or brown.

Melanins are found in humans, but also in other mammals and other animals, as well as in invertebrates or even in various microorganisms. In each of the organisms mentioned, the pigments from this group have a different function, but one thing can be said for sure: they are substances with extremely important functions.

Melanin: types

There are three different pigments in humans that belong to the group of melanins. They are:

  • eumelanin: it has a black-brown color and we have the most of it,
  • pheomelanin: yellowish-red dye,
  • neuromelanin: this form of natural pigment occurs within the nervous system - it can be found, among others, in in the so-called a bluish spot or black substance - it is produced by nerve cells and currently its function is still not entirely clear.

Melanin: production

Melanin is produced in the body by special cells called melanocytes. They are mainly present in the basal layer of the epidermis.

The pigment produced by melanocytes is stored in special vesicles called melanosomes. With time, these vesicles are transported to the higher layers of the skin, eventually reaching the area of ​​keratonocytes - there, finally, the dye is deployed, which from then on can perform its protective functions.
Melanin itself is produced in a cycle of complex transformations, the starting substrate of which is the amino acid tyrosine. The basic enzyme involved in these transformations, called melanogenesis, is tyrosinase.

Melanin: factors regulating its production

Certain factors can stimulate and others inhibit the melanogenesis process. StimulatingThe production of melanin is influenced by UV radiation - this is why, when we sunbathe in the summer season, our skin takes on a brownish shade (so much desired by some).

Other substances that may increase melanogenesis include alpha-melanotropic hormone (alpha-MSH) and adrenocorticotropin (ACTH).

The factors that may inhibit the production of natural pigments include, among others, various interleukins. Vitamins, such as vitamin A or vitamin B, as well as minerals, such as calcium or iron, also have an impact on the process of melanin formation.

Melanin: where can we find it?

It is melanin that determines the fact that some of us have a very fair complexion, while others have an exceptionally dark complexion. The color of human skin is influenced by the amount of melanin in it - black people have the most of it, people with fair skin have much less of this pigment.

The final skin color is influenced not only by the amount of dye, but also by the ratio of the amount of darker eumelanin to much lighter pheomelanin.

A similar relationship as in the case of skin concerns hair. When they contain large amounts of pigment - especially eumelanin - they have a dark color. Then, when the hair of a given person is dominated by pheomelanin, it is possible that they will have reddish or blonde strands on their head.

Melanin, however, can also be found in other structures of the body. It has already been mentioned that one of its types - neuromelanin - is present in the central nervous system. The dye can also be found within:

  • eyeball (it is melanin that is responsible for the color of our irises - dark irises are those with a lot of melanin, people with blue or green eyes have much less of this pigment)
  • adrenal glands (melanins are present in the reticular layer of these organs)
  • inner ear structure

Melanin: human functions

For many people, the color of hair or skin is extremely important, but influencing the color of these listed is not the primary task of melanin. This dye is primarily intended to protect human skin.

The UV radiation reaching with the sun's rays, unfortunately, is not he althy for our cells - it can, among others, provoke DNA damage which, in the worst case scenario, can lead to the development of a tumor. This is where the essential function of melanin comes in - this pigment primarily has a protective effect against UV radiation.

The above-mentioned melanin function is possiblethanks to the fact that the pigment has the ability to both absorb and scatter ultraviolet radiation.

In addition, the energy that is absorbed by melanin can be converted by it into another, which is much less harmful to the human body - we are talking about thermal energy.

At this point, it may become understandable why people who live near the equator have a much darker complexion than the citizens of our country.

In regions of the world such as Africa, exposure to solar radiation is much greater than, for example, in Poland.

For this reason, the inhabitants of the equatorial zone have much darker skin - the large amounts of melanin present in it are simply intended to protect them from increased exposure to UV radiation.

Melanin is effective for both the skin and the eyes. The dye protects delicate structures of the eye from exposure to ultraviolet radiation.

The more melanin, the lower the risk of UV radiation harming us is - this is why people with light eyes have an increased risk of developing various eye diseases related to the sun.

The functions of melanin mentioned above can be undoubtedly considered extremely important.

In fact, dyes from this group probably have other, also valuable functions.

It is possible that they are capable of binding and thus neutralizing various heavy metals. These dependencies have not yet been studied sufficiently, however, among others, is that in patients with Parkinson's disease - where neuromelanin may be depleted in the structures of the central nervous system - there may be increased deposition of iron in the brain tissue.

Melanin: functions in other species

The beneficial properties of melanin can be appreciated not only by humans, but also by other organisms. For example, in birds, feathers containing large amounts of melanin are much more durable than those with less pigments.

Melanin is also used by various fungi - specific ones, called radiotrophic ones, use a dye to absorb heat, which allows them to accumulate energy necessary for life processes.

Melanin - which, unfortunately, is not beneficial for people - can also be used by certain microorganisms. In pathogens, melanin may be a factor by which they will deceive the host's immune system and thus prevent them from being affected byliquidation.

Other pathogens, thanks to melanin, may be more resistant to drugs, be they antifungal or antibacterial.

Melanin: diseases associated with its abnormal amounts

There is probably no need to convince anyone that the role of melanin is extremely important. However, some he alth problems may be associated with this dye - they may result from both the insufficient amount of melanin in the body and its excess.

The condition in which the patient's body - especially in the skin or hair - has abnormally small amounts of melanin is known as albinism.

There is congenital albinism, which is a genetic disease and results from enzymatic disturbances in proteins involved in melanogenesis. However, vitiligo can also be acquired and is then usually associated with damage to the pigment-producing cells, the melanocytes.

However, various phenomena may also appear in connection with an excess of melanin.

As examples, various types of skin changes can be given here - for example the presence of freckles on the skin is associated with the appearance of areas with increased amounts of melanin.

Lentil stains or stains like coffee and milk, as well as some pigmented marks, also appear due to the local accumulation of increased amounts of melanin.

Another problem that - although indirectly - is related to melanin, is skin cancer. The most dangerous of them - which is malignant melanoma - comes from melanin-producing cells - melanocytes.

About the authorBow. Tomasz NęckiA graduate of medicine at the Medical University of Poznań. An admirer of the Polish sea (most willingly strolling along its shores with headphones in his ears), cats and books. In working with patients, he focuses on always listening to them and spending as much time as they need.

Category:

Dermatology