Amphetamines Reverse Parkinson's Disease Symptoms In Mice

From Duke University Medical Center

Amphetamines, including the drug popularly known as Ecstasy, can reverse the symptoms of Parkinson's disease in mice with an acute form of the condition, according to new research at Duke University Medical Center. The team reports its findings in the August 2005 issue of Public Library of Science (PLoS) Biology.

The researchers caution that the findings in animals do not suggest Parkinson's disease patients should find relief by taking amphetamines, which are drugs of abuse with many dangerous side effects. The findings rather indicate that drugs with similar chemical attributes might offer useful alternatives to current therapies, the researchers said.

The new mouse model enables the researchers to acutely eliminate dopamine, exposing systems contributing to the disease that may not have been obvious before. In the current study, the researchers treated mice unable to recycle dopamine with a drug that also prevented them from manufacturing the brain messenger. The brains of the mice therefore lack detectable levels of dopamine and the animals exhibit all the symptoms of Parkinson's disease for up to 16 hours. Those symptoms included severely impaired movement, rigidity and tremor. When treated with L-DOPA, the symptoms disappeared as the animals resumed normal movement.

Surprisingly, the researchers reported, treating mice lacking dopamine with high doses of amphetamine derivatives – including methamphetamine and MDMA, otherwise known as Ecstasy – reversed those symptoms. Ecstasy was most effective at counteracting the manifestations of Parkinson's symptoms in the mice, with the beneficial effects becoming more pronounced with increasing dose.

The researchers also report that low doses of amphetamines could, when combined with L-DOPA, potentiate minimally effective doses of L-DOPA in the mice. This could have important considerations in reducing some of the side effects of current therapy.

"Taken together, the findings indicate that Ecstasy can improve movement control independently of dopamine and, most importantly provide evidence that drug activation of other neuronal pathways may be sufficient to restore movement even in the virtual absence of dopamine neurotransmission."