Brain protein central to both Parkinson's, drug addiction ...( Scientists have identified a protein...)

Scientists have identified a protein that appears not only to be central to the process that causes Parkinson's disease but could also play a role in muting the high from methamphetamine and other addictive drugs.

The action of the protein, known as organic cation transporter 3 or oct3, fills a longstanding gap in scientists' understanding of the brain damage that causes symptoms like tremor, stiffness, slowness of movement and postural instability. While these are found mainly in patients with Parkinson's disease, there are more than three dozen other known causes of this array of symptoms, known as "parkinsonism."

In a paper published online this week in the Proceedings of the National Academy of Sciences, scientists at the University of Rochester Medical Center and Columbia University have shown that oct3, a protein that shepherds molecules into and out of cells, plays a critical role, bringing toxic chemicals to the doorstep of the brain cells that die in patients with Parkinson's disease. The team found that oct3 is involved in the brain's response to addictive drugs like methamphetamine as well.

Precisely what causes Parkinson's disease remains largely a mystery. Some cases have a known genetic basis, and most others are attributed to environmental causes or a combination of gene-environment interactions. Doctors know that symptoms of Parkinson's stem from the death of a very small, specialized group of brain cells known as dopamine neurons, which produce a chemical needed by another area of the brain to help us move freely. It's not until most of those brain cells have already died that patients begin to show symptoms.

For decades, scientists have been trying to understand why those cells die. The latest paper supports a role for astrocytes, a type of cell that is the most common in the brain but which has been often overlooked by scientists focused more on cells known as neurons that send electrical signals. As
'/>"/>