Runners, 'Potheads' Similar High: Activating Pleasure Receptors Allows Experience Without Drugs or Exercise

First Posted: Oct 07, 2015 11:45 AM EDT

Researchers have discovered that it may be possible to achieve a "runner's high," or the psychological "rewards" of drugs, without either running or taking drugs, by activating the pleasure and reward receptors in the brain.

The pleasure and reward receptors in the brain are similarly activated by both using dangerous drugs and exercising, which is one of the reasons exercise routines are often recommended as a major method of therapy for drug addicts.

Knowing this, a team of researchers, led by Frank Booth, a professor at the MU College of Veterinary Medicine, began their experiment by selectively breeding rats that exhibited extreme laziness and extreme activity. They then gave chemicals to the rats that either activated or shut off their mu-opioid receptors, the genes in the brains of rats and humans which release dopamine, a pleasure-inducing chemical. 

Greg Ruegsegger, a doctoral student and lead author of the study, noted that when the extremely active rats' receptors were activated, they were less inclined to exercise.

"These highly active rats would run on their wheels constantly," Ruegsegger said, according to the release. "However, when we chemically activated their mu-opioid receptors, those rats drastically reduced their amounts of activity. Since exercise and addiction to substances follow this same chemical process in the brain, it stands to reason that activating these receptors in people with dangerous addictions could provide the same rewards they are craving without the use of dangerous drugs or alcohol."

When their brains were examined, the team found 400 percent more of the reward receptors in the extremely active rats, compared to their lazy counterparts. This suggested to the team that the extremely active rats were active in order to receive these "rewards" from their mu-opioid receptors, potentially explaining why they voluntarily run so long and are active so often.

This belief of the team is backed up by the idea of a "runner's high," the healthy release of endorphins that many long-distance runners experience when partaking in several mile-long runs. Endorphins are the body's natural opiate painkillers, essentially a counterpart to the chemically produced morphine.

Runs that find the "sweet spot" between comfort and challenging in order to achieve the release of endorphins, according to a 2008 study form the University of Bonn.

"Most runners I have worked with experience endorphins when they are pushing their bodies, but not usually at max effort," says Cindra S. Kamphoff, Ph.D., director of the Center for Sport and Performance Psychology at Minnesota State University, according to Runners World.

The researchers also shut off the mu-opioid receptors in the active rats, and found that it similarly reduced activity in them, but it did not produce as drastic a change as turning on those receptors in the active rats. Researchers found that activating and shutting off the receptors in the lazy rats seemed to have no large effect on those rats' overall activity levels. 

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