A new study has identified several chemicals that might inadvertently activate brain regions responsible for reproductive functions, potentially triggering early puberty in women. One such compound, a musky scent once common in men’s fragrances, has been banned in the European Union but may still be present in products worldwide, including the US.
RISING TREND OF EARLY PUBERTY
Over the past century, the average age of menarche—the onset of menstruation—and breast development has been decreasing. This trend is observed globally, suggesting that environmental factors, rather than solely genetic ones, may play a significant role.
While genetic and socioeconomic factors contribute, the rapid global decline in puberty age hints at novel environmental triggers. Previous studies have struggled to pinpoint specific causes due to inconsistent results and limitations in research methods, including reliance on blood and urine samples collected from volunteers during waking hours.
FOCUS ON GNRH NEURONS AND KISSPEPTIN
Researchers from the US National Institutes of Health and Northwestern University concentrated their study on a network of neurons in the hypothalamus crucial for puberty onset. Gonadotropin-releasing hormone (GnRH) neurons are pivotal as they stimulate the pituitary gland to release signals that prompt the ovaries and testes to produce estrogen and testosterone.
ROLE OF KISSPEPTIN IN PUBERTY REGULATION
Kisspeptin, a neuropeptide, plays a role in this process. It affects neurons sensitive to stress and diet variations, making it an ideal target for studying environmental interference. Researchers used a lab-cultured tissue model to screen for substances that might disrupt GnRH and kisspeptin activity.
SCREENING PROCESS AND FINDINGS
The researchers screened approximately 10,000 substances from an Environmental Protection Agency library. They identified a few dozen compounds that interfered with GnRH and kisspeptin pathways.
Cholinergic Agonists and Musk Ambrette
Among the substances tested, cholinergic agonists, which mimic neurotransmitters involved in memory, motivation, and arousal, were prominent. One compound, musk ambrette, stood out. Previously used in cosmetics and fragrances, musk ambrette was banned in the EU in the 1990s due to neurotoxicity in rats. Despite this, it is still synthesized in India and China.
Environmental Presence and Health Risks
Musk ambrette’s resistance to degradation means it remains in the environment, posing potential health risks. Further testing on human and mouse hypothalamic cells, as well as young zebrafish, demonstrated that musk ambrette could stimulate brain areas involved in early puberty.
PUBLIC HEALTH IMPLICATIONS
The early onset of puberty is linked to increased risks of psychological issues, cardiovascular disease, and breast cancer. Alongside environmental chemicals, factors like obesity and dietary changes may contribute to earlier puberty. This multifactorial influence highlights the need for comprehensive research into environmental and lifestyle factors affecting puberty timing.
This study underscores the importance of understanding how environmental chemicals influence reproductive health. Ongoing research is needed to explore these links further and inform regulatory actions to mitigate potential risks.
