Study: Why meds don't help some epileptics

TRIANGLE PARK, N.C., April 16 (UPI) -- U.S. scientists say a study of a rodent model of epilepsy might solve a medical puzzle: why some epileptics don't respond to anti-epileptic medications.

Researchers at the National Institute of Environmental Health Sciences and the University of Minnesota discovered a neurotransmitter released during seizures, glutamate, turns on a signaling pathway, increasing production of a protein that could reduce medication entry into the brain.

"Our work identifies the mechanism by which seizures increase production of a drug transport protein in the blood brain barrier (or BBB), known as P-glycoprotein, and suggests new therapeutic targets that could reduce resistance," said David Miller of the NIEHS.

Miller said P-glycoprotein forms a functional barrier in the brain that limits access of foreign chemicals.

"The problem is that the protein does not distinguish well between neurotoxicants and therapeutic drugs, so it can often be an obstacle to the treatment of a number of diseases, including brain cancer," Miller said. Increased levels of P-glycoprotein in the BBB has been suggested as one probable cause of drug resistance in epilepsy.

The study that included scientists at Ludwig-Maximilians-University in Munich, Germany, will appear in the May issue of the journal Molecular Pharmacology.