Replenishing Levels of Specific Molecule May Improve Muscle Function

Replenishing levels of a molecule naturally occurring in the body  and essential for energy production called NAD+ could restore muscle function, according to scientists at the University of Pennsylvania.

The levels of NAD+ (nicotinamide adenine dinucleotide) in muscles decline with age and may also be compromised in muscle-wasting conditions such as muscular dystrophy.

“Loss of NAD+ might be a feature that has previously been under appreciated in these diseases,” David W. Frederick, the study’s first author and a member of the Baur laboratory at the Perelman School of Medicine, said in a press release.

In the study “Loss of NAD Homeostasis Leads to Progressive and Reversible Degeneration of Skeletal Muscle,” published in Cell Metabolism,  researchers used mutant mice in which they knocked-out a gene encoding for an enzyme essential for the production of NAD+. They reduced the levels of NAD+ in the muscle of the animal down to about 15 percent of the normal amount.

They then measured the muscle strength and endurance of the animals by measuring their activity on a treadmill. Although the muscles of the animals were still functional NAD+ loss over time resulted in progressive muscle weakness.

The researchers then gave the mice water enriched with nicotinamide riboside (NR) a form of vitamin B3 and a precursor of NAD+. The exercise capacity of the mice was completely restored after only one week.

“What was surprising was that we didn’t need to replenish those NAD+ levels completely to see the muscle function begin to improve again. Just a small amount went a very long way toward restoring metabolic function,” said Frederick. But he added a caution: “it is too early to know if this same biology will translate to humans”.