Scientists at the Karolinska Institutet in Stockholm, Sweden, has published the results of a study exploring the way that the gut microbiome influences the development of skeletal muscle mass in mice. Team head Sven Pettersson already understood from other research that the gut microbiome is greatly involved in a wide range of functions, including metabolism, immune function and organ function.
The researchers investigated two kinds of mice: the first was a “germ free” line that lacked any microbiome, and a more natural, wild-type mouse with an intact microbiome. After several rounds of tests, the scientists decided that the germ-free mice actually demonstrated more muscle atrophy and muscle weakness compared to the wild-type mice.
These germ-free mice even had reduced expression of the genes responsible for muscle growth. They had elevated levels of amino acids – which often signifies a poorly functioning liver – and lowered levels of serum choline. As a necessary precursor for the synthesis of acetylcholine, choline is vital for the functioning of this neurotransmitter.
Acetylcholine transmits signals between the nerves and the skeletal muscles – so a lack of choline and hence acetylcholine can mean a disrupted nervous and musculoskeletal system. This also explains why mice without a microbiome had lower muscle mass than mice with a microbiome. This has important implications since reduced muscle mass is strongly associated with the onset of various metabolic disorders.
The researchers also found that when they transplanted the gut microbiome from wild-type mice inro the germ-free mice, they were able to moderate some of this muscle atrophy, and reverse some of the metabolic dysfunction. When germ-free mice were treated with fatty acids that the gut microbiome ordinarily produces, they were temporarily able to restore muscle mass and strength.
The research group is still investigating these fascinating phenomena, and further studies are planned to better understand how the microbiome interacts with the development and maintenance of skeletal muscles. Nevertheless, we think you’ll agree that these findings have encouraging implications for human gut health.
Citations
https://stm.sciencemag.org/content/11/502/eaan5662
