By: Leyuan Zhou

In July 10th’s publication of Science, a study found that a chemical signal, triggered by exercise and sent from the liver, keeps elderly mice’s brains sharp. This information may help scientists create a drug that simulates the connection between the human liver and brain.

An abundance of studies in the past have shown that exercise, especially during old age, benefits the brain by mitigating the effects of memory declines. Scientists have long wished for an “exercise pill” that could potentially mimic the bodily perks of exercise in those who are prevented from exercising due to various health reasons.

Researchers at the University of California, San Francisco, conducted a study that showed the “rejuvenating effects of blood” from young mice. Over the course of 24 days, they injected sedentary elderly mice with the blood plasma of active elderly mice who had run on wheels for the six weeks leading up to the experiment. After eight injections, the research showed that the sedentary mice injected with the active mice’s plasma performed better on memory tasks than the active mice with the sedentary mice’s plasma. Upon comparison, there seemed to be more proteins produced by the livers of active mice.

One of those proteins produced in response to exercise is GPLD1, an enzyme. “The molecule snips other proteins off the outsides of cells, releasing those proteins to go do other jobs.” When GPLD1 performs these actions, its results may be similar to the brain benefits of exercise.

Saul Villeda, a neuroscientist at the University of California, San Francisco who was part of the research team, said that, “Getting the liver to produce this one enzyme can actually recapitulate all these beneficial effects we see in the brain in exercise.”

An increased amount of GPLD1 was the reason why the active elderly mice performed better on memory tasks than the sedentary ones, the researchers found. This is akin to elderly humans as well: those who are physically active (walking more than 7,100 steps per day) have more GPLD1 than those who are less active.

Despite the various virtues of having higher GPLD1 levels, there is scientific evidence that the levels of this protein are higher in people with diabetes, which may prove it to be negative.

Researchers are still unsure of the exact pros and cons behind different levels of GPLD1, but they suspect that it doesn’t only affect the brain– it changes blood composition as well.

Article source: https://www.sciencenews.org/article/boosting-liver-protein-may-mimic-brain-benefits-exercise

Additional sources: https://science.sciencemag.org/content/369/6500/167