Glioma, one of the most deadly and common types of brain tumor, is often associated with seizures, but the origins of these seizures and effective treatments for them have been elusive. Now a team funded by the National Institutes of Health has found that human gliomas implanted in mice release excess levels of the brain chemical glutamate, overstimulating neurons near the tumor and triggering seizures.
The researchers also found that sulfasalazine, a drug on the market for treating certain inflammatory disorders, can reduce seizures in mice with glioma.
About 80 percent of people with glioma will experience at least one seizure during their illness, often as the first symptom. About one-third of patients will develop recurring seizures, known as tumor-associated epilepsy. Sen. Ted Kennedy, D-Mass., whose death was caused by a malignant glioma in August 2009, was diagnosed after having a seizure 15 months earlier.
"Seizures are a frequent symptom of glioma and are often poorly controlled by epilepsy medications," said Jane Fountain, Ph.D., a program director at NIH's National Institute of Neurological Disorders and Stroke (NINDS). "Understanding why the seizures occur and how to counteract them could help us substantially improve the quality of life for people with glioma."
"People have assumed that tumors cause seizures by irritating the brain, but that really isn't a scientific explanation. We have now shown that the seizures are caused by glutamate release from the tumor," said Harald Sontheimer, Ph.D., a professor of neurobiology and director of the Center for Glial Biology in Medicine at the University of Alabama Birmingham (UAB). Dr. Sontheimer and his team published their results in Nature Medicine.
The research was supported by NINDS, including $934,698 in grants funded through the American Recovery and Reinvestment Act.
Glutamate serves as a chemical relay within the brain. Its release
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NIH/National Institute of Neurological Disorders and Stroke