For the first time, scientists have developed drugs that mimics the effects of endurance exercise. With the aid of two chemicals, Vihang Narkar, Ronald Evans and colleagues from the Salk Institute managed to turn regular lab rodents into furry Paula Radcliffes – mighty mice that were capable of running further and for longer than their peers. One of the drugs only worked in combination with exercise, but the other managed to boost stamina without it.
AICAR, is even more exciting, for it managed to increase the endurance of mice without a need for exercise. When mice were given the drug, even the inactive ones managed to run 44% farther and 23% longer than their peers. AICAR works by activating a gene called AMPK, which is also involved in muscle metabolism and switched on by exercise. In addition to AMPK, Narkar saw that AICAR switched on a set of 32 genes in the muscles of mice, the majority of which are also controlled by PPARd
AICAR improved endurance without the need for extra exercise. Narkar’s idea is that AMPK is so central to the genetic events triggered by exercise, that activating it directly with AICAR bypasses the need for any exercise.
That’s not to say that exercise is irrelevant – AICAR may have boosted endurance on its own, but not to quite the same extent that exercise normally does. Nonetheless, by chemically mimicking some of the benefits of exercise, the team’s hope is that the drugs will find a use in treating metabolic diseases such as obesity, or warding against muscle wasting and frailty. After all, keeping active has a wide range of benefits that go well beyond its effects on endurance.
There’s even some evidence to suggest that Narkar’s drugs may do more good than simply improving stamina. In some of the mice, they triggered fat loss as alongside increased endurance. PPARd controls hormone levels and heart muscle as well as skeletal muscle, while AMPK’s ability to lower blood sugar levels may be relevant to diabetics. The potential benefits (and risks) of manipulating these genes won’t be fully known until Narkar checks their effects in these other tissues.