TDK conference 2020

Endocrine disruptors are substances that can influence a living organism’s hormonal control even in small doses. By interfering with the endocrine system, a disruptor can topple the homeostatic balance, which is carefully maintained by the hormone system with the help of signal molecules and feed-back mechanisms.

Arsenic is present everywhere in the environment. It can be found in the air, natural waters and also in minerals, thus the intake of this element cannot be prevented.

According to our hypothesis, arsenic may act as an endocrine disruptor, disrupting the thyroid hormone system, which is an essential part of the development of juvenile organism and also necessary to maintain a healthy endocrine function in adults. We also assume that the direction and degree of arsenic effects may differ in different species.

To support our hypothesis, our experiments were carried out in vitro applying rat and mouse cerebellar granule cell cultures. As experimental endpoints, transcriptional expression of thyroid receptors α and β have been measured using quantitative real-time PCR analysis. Before the assays, cultures were treated with T3, arsenic treatment and T3 + arsenic.

According to our results, arsenic acts as an endocrine disruptor, since it significantly alters the thyroid hormone expression in both species, even in small doses. We showed that the expression of TRα and TRβ receptors are stimulated by arsenic in rat cell cultures, however in mice cultures it blocks the receptors’ expressions. Our results supported the idea that the endocrine system of rats and mice, at least with regard to the hormone system in question, show different vulnerability to arsenic. Indeed, rat cells are more sensitive to arsenic treatment than mice’s. Therefore, it can be concluded that interspecific differences in endocrine disruptor effects should be considered in the future testing of chemicals, and that particular disruptors may exert definitely different impact in different species, organs and tissues. Due to these differences, data from rat and mouse cultures are not interchangeable, rather they supplement each other.