Neuroendocrine homeostasis and endocrine-disrupting compounds

Hello, my name is Jan Czerniecki and I am going to tell you about the influence of endocrine-disrupting compounds on hormonal homeostasis. All physiological processes occurring in human body are precisely regulated to keep a specific state of balance called homeostasis. The crucial part of this regulation is realized using hormones - special molecules produced by specific organs. Their secretion is strictly determined and they are released in a right time and appropriate amount in specific circumstances. Human fertility, as many other processes, is regulated by hormones, especially by a special class of sex hormones such as estradiol, progesterone or testosterone, which belong to the group of steroid hormones.

Any disturbances of hormonal regulation can lead to a decrease in the reproductive potential and development of infertility. During the last few decades infertility became a significant problem in developing countries, and many couples attempting to conceive are affected by infertility. The reason of such phenomenon remains unknown. Although infertility is a complex problem and may be caused by many factors, disruption of hormonal homeostasis is also taken into consideration. Especially that a significant increase in male infertility factor is observed. Recently, the relatively new group of molecules has been identified, having a potential to disturb hormonal homeostasis. They appeared in the environment as a result of the development of new technologies and replacement of previously used substances by new materials.

Nowadays, plastics are ubiquitous and manufactured on a large scale. They are also used also in food industry for production of bottles and food containers. Even the inner side of cans is usually coated with plastics. Plastics are polymers produced in the polymerization process from monomers called plasticizers. Unfortunately, due to the specificity of a large-scale production, many molecules of a plasticizer remain unbound in the plastic structure. Therefore, they are released over time and penetrate the drinks and food stored in a plastic packaging, and then contaminate our organisms. Despite the fact that they can penetrate through the skin or be inhaled, the contaminated drinks and food are the main way of human exposure to plasticizers.

The chemical structure of plasticizers is similar to steroid hormones - the natural-control factors produced in our body. Maybe they are not identical, but their similarity is strong enough to cause some interference in the processes controlled by these hormones. And of course, in contrast to natural hormones, their influx into the human body is completely random. The key part of hormonal control are the receptors. They are usually protein structures with affinity to hormone molecules. After binding to a hormone, receptors can trigger a specific sequence of biochemical events. The same hormones often have more than one type of the receptor. They are located in different tissues or can be a part of different biochemical control pathways, thus extending the range of hormone activity.

The molecules similar to hormones may act

in two different ways: as agonists or antagonists. Agonistic way of acting means that after binding to the receptor, molecules activate the same sequence of biochemical events and their effect is similar to the genuine hormone. However, when the binding of the molecule to the receptor leads to its blockage without triggering any further steps of hormonal regulation pathway, we are dealing with the antagonistic way of molecule’s action. The molecules of plasticizers can either act as agonists or antagonists of steroid hormones depending on the receptor type or tissue specificity. Disrupting action of plasticizers’ molecules was postulated with reference to infertility development.

It was shown that they cause estrus cycle dysregulation, decrease sperm quality and its fertilizing potential, as well as negatively affect the development of the fetus during pregnancy. Now we know that their negative effects are not limited only to fertility disorder. They can also interfere other physiological processes such as brain development, bone metabolism, insulin resistance and type 2 diabetes development, or even stimulate breast ovarian and prostatic tumorigenesis. To conclude, we can say that plastics are cheap, easy to form and extremely durable. It is not possible to eliminate them from our surrounding. For many of us it would be like a return to the stone age.

However, it should be remembered that they are not as biochemically indifferent as they once seemed, and they can be a source of endocrine disrupting chemicals, potentially harmful to our organism. Since the digestive system is the main entrance for endocrine disrupting compounds to our body, we should try to reduce the contact of food or drinks with plastic containers to the minimum, to avoid their contamination. The high quality of food can be diminished by materials used for packaging and storage