Marijuana-Like Brain Chemicals Ease Parkinson's Symptoms in Mice

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"The mice that didn't have dopamine in that circuit are completely frozen," Kreitzer said. "They don't walk around at all. To restore plasticity, we tried to activate the dopamine signal."

The mice were given both dopamine and a drug being developed for treatment of anxiety, which acts by slowing the breakdown of brain cannabinoids. "The animals started walking around immediately," Kreitzer said. "There was a five- or sixfold increase in motor activity. If you inhibit the breakdown of these endocannabinoids, you enhance activity even in mice that lack dopamine."

Research now will go in a number of directions, Kreitzer said. "We'd like to understand some other functions of these compounds," he said. Several stages of animal work must be done before human trials can be considered, Kreitzer added.

"A potential role for endocannabinoids for Parkinson disease represents an exciting new area for Parkinson research," said Dr. Michael S. Okun, medical director of the National Parkinson Foundation, which helped fund the research.

Although more study is needed, the work "sheds some light on potentially relevant targets and strategies for treatment of this neurodegenerative disease," said Okun, who is also co-director of the Movement Disorders Center at the University of Florida, Gainesville.

More information

There's more on Parkinson's disease at the National Parkinson Foundation.