Epilepsy may start in "ignored" brain cells

29 Aug 2005

Star-shaped brain
cells, known as astrocytes, appear to play a key role in the
development of epilepsy, according to new research published by the
journal Nature Medicine.

found that astrocytes can be responsible for setting off a seizure's
abnormal electrical activity in the brain by sending out a chemical
that triggers other brain cells to fire ‘out of control'.

The researchers at the University of Rochester Medical Center are hopeful the results will give doctors and pharmaceutical firms a new target in efforts to treat and prevent epilepsy.

Dr Maiken Nedergaard, professor at the medical centre's department of neurosurgery, commented:

main function of astrocytes is to maintain a healthy environment for
neurons [the nerve cells that send electrical signals across the
brain]. The electrical signalling in the brain is so sophisticated that
it's crucial that the environment be optimal. There's not much room for
error. When the astrocytes start acting abnormally, it's easy to see
how serious disease might result."

already knew that an early sign of epilepsy are abnormal brain cells
called reactive astrocytes - over-sized, bloated, star-shaped cells
that no longer function properly. It was commonly thought that reactive
astrocytes were caused by epilepsy, not the other way round. However,
in this study, the researchers showed that astrocytes actually generate
seizure activity and were linked to a brain chemical, glutamate, which
is known to be a key player in the development of epilepsy. They showed
that glutamate, which hypes up neurons and can make them fire
uncontrollably, is released by astrocytes and can trigger seizure-like
activity in the brain.

Dr Nedergaard concluded:

opens up a new vista in efforts to treat epilepsy. It might be possible
to treat epilepsy not by depressing or slowing brain function, as many
of the current medications do, but by targeting brain cells that have
been completely overlooked. We are hopeful that someday, this will be
very beneficial to patients."