In a new study, researchers found that blocking the activity of a single protein in old mice for one month restores mass and strength to the animals’ withered muscles and helps them run longer on a treadmill.
The old mice are about 15% to 20% stronger after one month of treatment, and their muscle fibers look like young muscle.
Considering that humans lose about 10% of muscle strength per decade after about age 50, this is quite remarkable.
Conversely, increasing the expression of the protein in young mice causes their muscles to atrophy and weaken.
The protein in the study hasn’t previously been implicated in aging.
The researchers show that the amount of the protein, called 15-PGDH, is elevated in old muscle and is widely expressed in other old tissues.
Experiments they conducted in human tissue raise hopes for a future treatment for the muscle weakness that occurs as people age.
The research was conducted by a team at the Stanford University School of Medicine.
Muscle loss during aging is known as sarcopenia, and it accounts for billions of dollars of health care expenditures in the United States each year as people lose the ability to care for themselves, experience more falls, and become increasingly less mobile.
It is due to changes in muscle structure and function: The muscle fibers shrink and the number and function of the cellular powerhouses known as mitochondria dwindle.
Previously, the team found that a molecule called PGE2 can activate muscle stem cells that spring into action to repair damaged muscle fibers.
In this study, they found that compared with young mice, the protein 15-PGDH levels are elevated in the muscles of older animals, and the levels of prostaglandin E2 are lower.
They found a similar pattern of 15-PGDH expression in human muscle tissues, like those from people in their 70s and early 80s expressed higher levels than those from people in their mid-20s.
The researchers administered a small molecule that blocks the activity of 15-PGDH to the mice daily for one month and assessed the effect of the treatment on the old and young animals.
They found that, in old mice, even just partially inhibiting 15-PGDH restored PGE2 to similar levels found in younger mice.
The muscle fibers in these mice grew larger, and were stronger, than before the treatment.
When the team performed the reverse experiment—overexpressing 15-PGDH in young mice—the opposite occurred.
The animals lost muscle tone and strength, and their muscle fibers shrank and became weaker, like those of old animals.
Finally, the researchers observed the effect of PGE2 on human muscle fibers.
They are hopeful that these findings may lead to new ways to improve human health and impact the quality of life for many people.
ing One author of the study is Helen Blau, Ph.D., a professor of microbiology and immunology.
The study is published in Science.
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