A variety of age-related diseases – including bone weakness, sexual dysfunction, diabetes, cancer and cardiovascular disease – can be predicted by a single hormone that appears at a constant level in men throughout their lives, new research reveals.
This hormone is INSL3 and it appears for the first time during puberty. After that, its levels only drop slightly in old age. This consistency, and the young age at which it occurs, makes INSL3 valuable to scientists – and possibly men’s health.
Someone with lower levels of INSL3 at a young age will likely have lower levels of the hormone in old age, new research suggests. If this translates into a greater risk of health complications, as the study suggests it may, these health risks could potentially be addressed many years earlier.
“Understanding why some people are more likely to develop disability and disease as they age is vital so that interventions can be found to ensure that people not only live long lives but also live healthy lives as they age,” he says. reproductive endocrinologist Ravinder Anand-Ivell; from the University of Nottingham in the United Kingdom.
“Discovering our hormone is an important step in understanding this and will pave the way not only to help people individually but also to help alleviate the care crisis we face as a society.”
INSL3 is produced by the same cells in the testes that produce testosterone. Unlike testosterone, INSL3 does not fluctuate as men become adults.
To monitor the level of INSL3 in the blood, researchers took samples from more than 2,200 men at eight different regional centers in Europe. The men’s INSL3 levels remained stable over time and also varied significantly between individuals, enough to separate health risks.
The researchers suggest that INSL3 levels in the blood correlate reliably with the number and health of Leydig cells in the testicles – having fewer of these cells and less testosterone has also been linked to many health problems in later life.
“Now that we know the important role this hormone plays in predicting the disease and how it varies between men, we are turning our attention to finding out which factors have the greatest effect on the level of INSL3 in the blood,” says molecular endocrinologist Richard Ivell from the University of Nottingham.
“Preliminary work suggests that early nutrition may play a role, but many other factors such as genetics or exposure to certain environmental endocrine disruptors may play a role.”
In nine categories of morbidity reported by participants in questionnaires, including cancer, diabetes and cardiovascular disease, INSL3 was associated with an increased risk of morbidity in eight of them (only depression was found to have no association in this study).
But when the researchers adjusted for other hormonal and lifestyle factors, such as BMI and smoking status, most of these associations with INSL3 disappeared, except for high blood pressure and cardiovascular disease.
And testing whether INSL3 levels in blood samples from a subset of men could predict health outcomes about four years later, lower hormone levels were associated with seven of nine comorbidity categories. But again, this was done without considering other factors.
One area the scientists are keen to explore in future studies is how INSL3 relates to sexual health, with its strong link to testosterone, but this was not covered in detail in this particular piece of research.
Future studies should also “focus on longer time periods to determine whether INSL3 measured in younger or middle-aged men … is truly predictive of the later onset of an age-related health issue,” the researchers conclude.
If the link between INSL3 and these health risks is substantiated by further studies, and scientists are able to pinpoint exactly why the link exists, it means that preparations can be made much earlier to detect – and stop – a variety of age-related health problems to occur.
“The holy grail of aging research is to reduce the fitness gap that occurs as people age,” says Anand-Ivell.
The research has been published in Frontiers in Endocrinology.