Drug Stops Brain Cell Death for Mice with Huntington's

A drug used to treat symptoms of Huntington's disease in some countries has been found to prevent the death of brain cells in mice according to UT Southwestern Medical Center. The study was published in the July 25 issue of The Journal of Neuroscience.

"The drug can actually prevent brain cells from dying," said Dr. Ilya Bezprozvanny, associate professor of physiology at UT Southwestern and senior author of the study in a press release. "It's much more important than people thought."

Huntington's disease is a fatal genetic condition that normally displays symptoms between 30 and 45 years, as reported by the Huntington's Disease Society of America. One in 10,000 people in America alone have the disease, and it is estimated that an additional 200,000 people are at risk for developing the disease.

If a person is found carrying the gene for Huntington's, the person will eventually develop symptoms that identify the disease. They will also have a 50 percent chance of passing it onto their children. Symptoms include uncontrollable movements (called chorea) and deterioration of reasoning ability and personality. However, these symptoms occur after a significant amount of brain cells have died.

A genetic test to detect the gene has existed for several years, but many people with a family history of Huntington's have resisted being tested. They cite reasons such as no cure and worry that they will loose their health insurance. Although treatments exist to prevent symptoms, there is no current way to lessen the progress of Huntington's.

The study used genetically engineered mice to mimic Huntington's disease, a hereditary condition. The mice were then given the drug tetrabenazine (TBZ), which is approved for use in other countries to treat uncontrollable muscle movement in Huntington's disease. It works by blocking dopamine, the chemical that nerve cells use to signal other nerve cells.

Bezprozvanny's study shows that the drug prevents the death of brain cells in mice. It focused on the area of the brain called the striatum, which helps relay motion and higher thought signals to several other brain areas. Huntington's leads to the death of medium spiny neurons, which are the primary part of the striatum.

When TBZ was administered to the mice, it not only prevented some of the symptoms of Huntington's disease, but also prevented actual brain cell loss. It is believed that this research could lead to new areas of study to prevent initial brain cell death long before symptoms are apparent.

"More research is needed to determine whether this protective effect might also be present in humans, and also whether at-risk people would benefit from the drug," Dr. Bezprozvanny said.

In the press release, Dr. Bezprozvanny cautions that studies on humans will be difficult due to the required amount of patients. Instead, he plans on continuing his trials on animals using TBZ just after initial symptoms are detected.

SOURCES:

"Drug protects brain cells in Huntington's disease model, researchers find." UT Southwestern Medical Center. URL: (http://www.utsouthwestern.edu/utsw/cda/dept353744/files/396135.html)