Protein Involved in Parkinson’s Might Help Fight Drug Addiction

A protein known as oct3 that normally guides molecules in and out of cells but can kill dopamine neurons—which play a key role in both movement and feelings of euphoria—in diseases like Parkinson’s was found to mute the high that drug users experience from methamphetamines and similar substances.

Oct3 helps cells called astrocytes absorb excess dopamine in the space around neurons. If dopamine isn’t soaked up as quickly or efficiently as usual, people can feel euphoric—but they can also experience brain damage. In patients with Parkinson’s, oct3 would need to be decreased so that more dopamine (and thus movement) remains in the brain; on the other hand, drug addicts would need increased oct3 activity to soak up the excess dopamine.

Scientists at Columbia University and the University of Rochester medical centers in New York found that blocking or genetically removing oct3 in mice kept a toxic brain chemical (MPP+) away from the neurons and inside the astrocytes. This discovery is helping scientists understand why the death of dopamine neurons lead to Parkinson’s symptoms like tremors, stiffness, and slowness of movement, and it also suggests that people with low oct3 activity may have a higher potential for drug addiction.

Kim Tieu, an assistant professor in environmental medicine at Rochester, said, “How you choose to manipulate the function of oct3 depends on the source of the toxic molecules.” She continued, “You would try to lessen its effects in a condition where it makes a toxic molecule available to vulnerable cells, as illustrated in the current model of Parkinson’s disease. But in the case of drug addiction, you might try to increase it, to lessen the impact of a drug like methamphetamine.”

Though there is currently no drug that can block or boost oct3 in humans, finding one could eventually help people suffering from drug addiction or Parkinson’s.

Source: Forbes.com, May 2009