The hormone known as the “Insulin-like peptide 3” (INSL3), provides an exciting breakthrough among scientists in the prevention of age-related diseases in men. The new study published in Frontiers in Endocrinology describes INSL3, secreted in men by the mature Leydig cells of the testes as a marker of hypogonadism and other age-related diseases.

The study which was conducted by researchers from the University of Nottingham found that examining the levels of INSL3 in men helps in early prediction and offers vital insight into the likely development of diseases later in life. 

In addition, they discovered that INSL3 levels have a strong link with various age-related diseases such as bone weakness, hypertension, heart diseases, sexual dysfunction, and diabetes.

INSL3 is a hormone that is produced by the same cells that produce testosterone in the male reproductive system. However, the levels of testosterone in the blood tend to vary all through a man’s lifespan, when compared to INSL3 which remains constant for decades right from childhood to adulthood (18 – 20 years) and decreases only to an extent as men grow older (30 or 40 years and older). For this reason, the scientists suggest this INSL3 hormone sets itself apart from other measurable parameters as a better, authentic, and more dependable biomarker of age-related morbidity and disease status.

“The holy grail of aging research is to reduce the fitness gap that appears as people age. 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 people not only live a long life but also a healthy life as they age”, explains Professor Ravinder Anand-Ivell, co-author of the study and associate Professor at the University of Nottingham.

Importantly, this is the latest of all 3 studies into this hormone. Researchers reported results from a total of 3,369 male participants between the ages of 40 – 79 years. Each came from 8 centers in East, West, South, and North Europe. The second stage of the study was conducted during a follow-up period of over an average of 4.3 years.

With the aid of questionnaires, the researchers interviewed the participants to collate data on disease occurrence, diet, lifestyle factors as well as physical and cognitive functioning. They also collected their blood samples for analysis in both stages of the study. This was in a bid to compare changes in hormonal levels in the participants over time.

At the end of the study, the researchers found that compared to testosterone alone, the levels of INSL3 remain a stable parameter across all ages in men. On top of that, they found that the levels of INSL3 in the blood vary greatly up to 10-fold among the normal male population, even in younger healthy men. 

For the most part, the findings simply imply a man having a high INSL3 at a young age still maintains a high INSL3 as he advances in age. On the flip side, a low level of INSL3 when young will persist into older age, thereby increasing the susceptibility to age-related diseases.  

“Now we know the important role this hormone plays in predicting disease and how it varies amongst men. We are turning our attention to finding out what factors have the most influence on the level of INSL3 in the blood. Preliminary work suggests early life nutrition may play a role, but many other factors such as genetics or exposure to some environmental endocrine disruptors may play a part”, concludes the lead study author, Professor Richard Ivell. 

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