PGC-1alpha is also required for the normal operation of genes that control the development of neuromuscular junctions (NMJ) ?sites on muscle fibers where nerves attach and signal the fibers to contract. Part of the reason that exercise builds stronger muscles is that it increases PGC-1alpha activity. Conversely, disease or lack of exercise reduces PGC-1alpha activity, causing a loss of NMJ function and weakening, or atrophying, of muscles.
Spiegelman’s team had previously bred a strain of mice with higher-than-normal levels of PGC-1alpha in their muscles. Also available for the research was a mouse model of Duchenne muscular dystrophy, the MDX mouse. In the new experiment, the scientists bred male high-PGC-1alpha mice with female MDX mice (the muscular dystrophy gene is carried by females in mouse and in humans.) As a result, the offspring of these matings had muscular dystrophy but also had elevated PGC-1alpha. Using exercise and chemical tests, the researchers compared muscle function in the offspring with MDX mice having no additional PGC-1alpha.
Both sets of rodents were run on a treadmill for one hour, then again 24 hours later. Normal mice completed the runs easily on both days, while untreated MDX rodents were exhausted halfway through each run. The MDX mice with increased PGC-1alpha activity performed almost as well as normal mice on the first day; their performances decreased on the second day, but they still did better than the untreated MDX mice on both runs.
The exercise tests and microscopic and chemical examinations of the muscles showed that boosting PGC-1alpha caused “a clear and substantial improvement in the structure and function of skeletal muscle in this disease model,?the scientists wrote.
Source:Dana-Farber Cancer Institute