Scientists discover key enzyme in muscle aging process.[Lammeyer/iStock]
Scientists discover key enzyme in muscle aging process.[Lammeyer/iStock]

There is a double standard in the aging process, as we are often told that men age more gracefully than women. Well, what if there was a physiological reason behind the insidious process? It may be of little comfort to those women currently experiencing the ill-perceived effects of getting older, yet researchers at the University of Birmingham, who have identified the role of a key enzyme in muscle wasting, believe that a better understanding of this process could aid in the development of ways to prevent many of aging’s adverse effects.      

The investigators found that the enzyme 11β-HSD1, which is responsible for activating the steroid hormone cortisol, was increased within the muscle tissue of older females.

“As yet, we don't know why it appears to only occur in women,” stated Zaki Hassan-Smith, Ph.D., clinical lecturer at the University of Birmingham and lead author on the current study. “It is obviously an interesting area for further research. We are planning to look at whether hormones such as estrogens could be involved.”

The findings from this study were published recently in the Journal of Clinical Endocrinology and Metabolism “Gender-Specific Differences in Skeletal Muscle 11β-HSD1 Expression Across Healthy Aging.”

Specifically, Dr. Hassan-Smith and his colleagues studied 134 healthy volunteers between the ages of 20-80. The subjects underwent both physical and biochemical tests including, body composition analysis by bone densitometry, jump plate mechanography, grip strength analysis, baseline biochemical profiling, urine collection, and vastus lateralis (thigh) muscle biopsy  

The investigators found that the expression of 11β-HSD1 was increased almost threefold in women over the age of 60. However, in male participants no difference was seen.

Additionally, higher levels of 11β-HSD1 aligned with increased levels of cortisol, reduced grip strength, insulin resistance, and a poorer body composition profile.

Dr. Hassan-Smith and his colleagues didn’t choose to study 11β-HSD1 at random, as they had been previously doing research on Cushing Syndrome, a rare endocrine disorder cause by high cortisol levels, and knew that the enzyme was involved.

“Looking at this particular enzyme seemed like an intriguing way forward,” explained Dr. Hassan-Smith. “We knew how it works in relation to Cushing's Syndrome, which is characterised by similar symptoms, and thought it would be worthwhile applying what we knew to the ageing population.”

Currently there is no treatment for age related muscle wasting (sarcopenia), but a number biopharmaceutical companies are developing inhibitors 11β-HSD1, many focusing on treatments for diabetes. The University of Birmingham team is excited to adapt some of these developing inhibitors for their studies and move their research forward in trying to combat muscle aging.  

“The next stage is a 'proof of concept' study to look at the effects of these inhibitive pharmaceuticals on muscle function, before opening it up into a clinical trial,” concluded Dr. Hassan-Smith. “It's an as yet unexplored area that could yield beneficial results for a problem that is becoming more prevalent as our lifespans increase.”

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