Lou Gehrig’s disease, or Amyotrophic Lateral Sclerosis is a progressive, fatal, adult-onset disease that occurs in roughly 0.0015 percent of the human population, and roughly the same percent of the population in mice — the model organism that was used in the UCSD study. 

About 5,500 people die from ALS each year. Humans afflicted with ALS generally begin to see symptoms in their late forties and live only three to five years after diagnosis. Most mice begin exhibiting symptoms of ALS at three or four months, and live a few weeks at most.

The medication Rilutek is the only extant treatment for ALS aside from pain medication. Rilutek can extend survival times for many late stage ALS patients by months. It does not provide any relief from symptoms.

A faulty enzyme, copper-zinc superoxide dismutase (SOD1) is implicated in both mouse and human ALS. How a faulty copy of SOD1 causes ALS remains unknown, however. 

The researchers tested the muscle and cardiovascular functioning of the mice to see if there were any significant physiological differences between normal mice that didn’t have ALS and ALS-positive mice that were injected with the gene for PCG-1?.

ALS-positive mice of both varieties were also made to run on small treadmills until they fell off and even electrical shocks would not compel them to get back up and keep running.

The team used two dyes, hematoxylin and eosin, to determine what fraction muscle cells in a tissue were actively performing mitosis at a given time. 

ALS-positive mice that had not received any treatment demonstrated slower response times, diminished endurance and reduced rate of mitosis, or cell reproduction. ALS-positive mice that had been treated with PCG-1?, on the other hand, demonstrated none of these deficiencies. In fact, they performed as well on the fitness tests as normal mice without ALS.

However, though they did not exhibit any symptoms of ALS, the mice treated with PCG-1? died just as early as the other ALS-positive mice: there was no significant difference in survival time.

Despite this, the researchers said they are optimistic. One of the most heart-wrenching aspects of ALS is the suffering that patients face from diminished muscle function. In their paper, published in the May 2012 issue of Cell Metabolism, the researchers concluded that compounds including PGC-1? “increase muscle function, reduce atrophy and improve daily physical activity, thus resulting in a better quality of life for patients.”