Researchers at the University of Oulu in Finland have identified a previously unknown biological mechanism in humans that may explain how certain medications and environmental chemicals impact the body’s sex hormones.
This discovery represents a significant step forward in understanding endocrine-disrupting compounds – chemicals that can interfere with the body’s hormonal system. Understanding these disruptions is crucial, as hormonal balance plays a vital role in numerous bodily functions.
The study’s findings were published in the specialized journal Basic & Clinical Pharmacology & Toxicology.
The Role of PXR in Monitoring Body Chemicals
The research focused on a biological receptor known as the pregnane X receptor (PXR), a protein that functions as a sensor for chemical levels within the body.
Whereas PXR is already known for its role in regulating how the liver processes medications, the novel study revealed it too plays a key role in controlling the production of another protein called SHBG.
SHBG is responsible for transporting sex hormones – including testosterone and estrogen – in the bloodstream. It also determines how much of these hormones are actually available for use within the body.
Experiment Using a Common Antibiotic
For the study, researchers administered the antibiotic rifampicin to a group of healthy volunteers for one week.
Rifampicin is known as a potent activator of the PXR receptor.
The results showed a clear effect: the level of SHBG protein in the blood doubled in most participants, and total testosterone levels increased in male participants. Further laboratory tests on liver cells confirmed that rifampicin increased SHBG production, but this effect disappeared when researchers deactivated the PXR receptor, confirming its essential role in the process.
A New Biological Pathway Explains Chemical Impact
“We have known for some time that certain chemicals can affect the balance of sex hormones,” said lead study researcher Jani Hukkanen, Professor of Internal Medicine at the University of Oulu.
He added that the new study revealed a biological pathway linking PXR, SHBG, and testosterone – PXR → SHBG → Testosterone – illustrating how these substances can influence hormone levels in the human body.
Everyday Chemicals May Affect Hormones
Researchers explained that the PXR receptor can be activated by a wide range of chemicals, including certain medications, compounds found in food, and environmental chemicals such as pesticides, flame retardants, and plastic additives.
This finding could have broad implications for understanding how the body interacts with everyday chemicals.
Importance of the Discovery for Public Health
Scientists believe that understanding this new mechanism could aid predict the effects of drugs and chemicals on the hormonal system, develop safer pharmaceuticals and chemicals, and potentially reduce harmful health effects before they occur.
Researchers hope these results will contribute to improved risk assessment related to chemical exposure in the environment and daily life.
