Injecting new neurons helps tone down epileptic seizures

Ars Technica » Scientific Method 2013-05-07

Transplanted neurons (green) successfully integrated into the brains of adult mice.
RF Hunt and SC Baraban

When most people think of the nervous system, they think of it as a hub of activity. Sensations trigger nerves, which activate the ones they're connected to, eventually producing a response. What's often overlooked is the fact that shutting nerves down is just as important. Entire classes of nerves exist solely to tell their neighbors to quiet down, while Parkinson's disease is caused by the failure of a circuit that ultimately helps shut down muscle activity.

Another disease that's caused by excessive nerve activity is epilepsy, where the aberrant activation of nerves causes seizures. Researchers decided to try reversing this effect by adding additional inhibitory neurons, derived from embryonic cells, to specific regions of the brains of epileptic mice. The approach worked, which means their next step will probably involve trying to do the same thing with neurons derived from stem cells.

Although epilepsy is a complicated disease in humans, it's possible to model it in mice using a drug called pilocarpine, which activates receptors for the neurotransmitter acetylcholine. Used appropriately, pilocarpine is a valuable drug. But when given systemically (for example, injected into the blood stream), the drug enters the brain and causes excessive neural activity. This can result in long-term changes to the architecture of many neurons in the brain, creating a variety of symptoms that may include seizures, hyperactivity, and altered spatial memory.

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