Science may soon give us a pill that makes us get up off the couch and hit the gym.
Swiss researchers have discovered that elevating the amount of erythropoietin, a hormone more commonly known as epo, in the brains of mice led them to be more active. What's more, it did so without causing the erythropoiesis, or elevated red blood cell counts, that typically occurs when epo is used to boost performance.
Anyone who follows cycling knows about epo. It is a widely and illegally used performance-enhancing drug. It is more commonly and legitimately used to treat various types of anemia following chemotherapy or kidney failure. In these cases, though, the drug is administered in multiple small doses over time. Swiss researchers, in a study published in The Journal of the Federation of American Societies for Experimental Biology, found epo has a far more dramatic effect (.pdf) in large doses.
"Here we show that epo increases the motivation to exercise," Max Gassmann of University of Zurich said in a statement.
The discovery raises the possibility of creating a drug that would help people achieve healthier lifestyles and chip away at an epidemic of obesity caused in part by the fact we get half as much exercise as we should. Beyond that, any drugs derived from the research could be used to treat mental illnesses where physical activity is known to improve mood and behavior.
"It's a very exciting finding," said Dr. Gerald Weissmann, the journal's editor-in-chief.
The researchers used three groups of mice to test the effect of epo. Some received no treatment, some were injected with human epo, and some were genetically modified to produce human epo in the brain. Compared to the mice that received no additional epo, the doped mice showed significantly higher running performance without the damaging increase in red blood cells.
When used in repeated small dosages as a performance-enhancing drug, kidney-derived epo stimulates the production of red blood cells, enhancing oxygen delivery and utilization. However, when given as acute high doses of 2,000 IU (international units), epo crossed the blood-brain barrier, becoming a brain hormone, the study found. This new role for the hormone doesn't alter red blood cell production. Mice treated with this epo improved their exercise performance "independent of changes in total hemoglobin mass, as well as in whole blood volume and cardiovascular parameters," the researchers wrote in the report. "This novel fining builds a more complete understanding regarding the central effects of endogenously produced and exogenously applied epo on exercise performance."
"It will still be an enhancing drug, just not bad for you," Weissmann said. "We can now look for substances like epo that have a similar effect. If brain epo makes you want to do it, without actually building the blood cells, we can now look for similar things that aren't harmful. It shouldn't be used just to build up your stamina."
Any drugs or treatments that might stem from the study could be used for more than helping people lose weight and improve their health. They also could be used to assist in building endurance or rebuilding muscle mass to hasten the recovery from illness, or to help treat mental illness.
"It's not therapy," Weissmann said, "but it's something people can start thinking about so we can think about ways to build up the brain's epo. It's not just for athletes. Suppose you're debilitated, sick or depressed. Get a drug that worked this way, and we'd be in good shape."
