XML Feed for RxPG News   Add RxPG News Headlines to My Yahoo!   Javascript Syndication for RxPG News

Research Health World General
 
  Home
 
 Latest Research
 Cancer
 Psychiatry
 Genetics
 Surgery
 Aging
 Ophthalmology
 Gynaecology
 Neurosciences
  Memory
  Regeneration
  Stroke
  Brain Diseases
   Epilepsy
  Headache
  Spinal Cord Diseases
  Demyelinating Diseases
  Neurodegenerative Diseases
  Taste
  Trigeminal Neuralgia
 Pharmacology
 Cardiology
 Obstetrics
 Infectious Diseases
 Respiratory Medicine
 Pathology
 Endocrinology
 Immunology
 Nephrology
 Gastroenterology
 Biotechnology
 Radiology
 Dermatology
 Microbiology
 Haematology
 Dental
 ENT
 Environment
 Embryology
 Orthopedics
 Metabolism
 Anaethesia
 Paediatrics
 Public Health
 Urology
 Musculoskeletal
 Clinical Trials
 Physiology
 Biochemistry
 Cytology
 Traumatology
 Rheumatology
 
 Medical News
 Health
 Opinion
 Healthcare
 Professionals
 Launch
 Awards & Prizes
 
 Careers
 Medical
 Nursing
 Dental
 
 Special Topics
 Euthanasia
 Ethics
 Evolution
 Odd Medical News
 Feature
 
 World News
 Tsunami
 Epidemics
 Climate
 Business
Search

Last Updated: Aug 19th, 2006 - 22:18:38

Epilepsy Channel
subscribe to Epilepsy newsletter

Latest Research : Neurosciences : Brain Diseases : Epilepsy

   DISCUSS   |   EMAIL   |   PRINT
Astrocytes appear to play a key role in development of epilepsy
Aug 15, 2005, 17:50, Reviewed by: Dr.

"People have thought that reactive astrocytes were caused by epilepsy, not that they could be the cause."

 
Star-shaped brain cells that are often overlooked by doctors and scientists as mere support cells appear to play a key role in the development of epilepsy, researchers say in a study published on-line August 14 in Nature Medicine. It's one of the first times scientists have produced firm evidence implicating the cells, known as astrocytes, in a common human disease.

Scientists found that astrocytes can serve as ground zero in the brain, setting off a harmful cascade of electrical activity in the brain by sending out a brain chemical that triggers other brain cells to fire out of control.

While it's impossible to tell at this early stage what effect the finding will have on treatment, the investigators 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 the disease.

"This 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," says Maiken Nedergaard, M.D., Ph.D., professor in the Department of Neurosurgery and a researcher in the Center for Aging and Developmental Biology, who led the research. "We are hopeful that someday, this will be very beneficial to patients,"

When most people and many scientists think of brain cells, they think of neurons, the nerve cells that send electrical signals and are at the heart of what is considered to be brain activity. In diseases like Alzheimer's, Parkinson's and Huntington's diseases, it's the neurons that become sick and die, and so they are the focus of intense study.

But neurons represent just a small proportion of brain cells. Astrocytes are present in vastly greater numbers there are approximately 10 times as many astrocytes as neurons in the human brain. Nedergaard is part of a growing group of scientists who are focusing on the pivotal role that astrocytes may play in several human diseases.

"The main function of astrocytes is to maintain a healthy environment for neurons," says Nedergaard, whose study was funded by the National Institute of Neurological Disorders and Stroke. "The electrical signaling 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."

Last year she showed that astrocytes magnify the damage to neurons after spinal cord injury. And currently she's looking at their role in Alzheimer's disease.

Nedergaard notes that in epilepsy, scientists have long known that an early sign of the disease in the brain are abnormal cells called reactive astrocytes over-sized, bloated, star-shaped cells that no longer function properly. "People have thought that reactive astrocytes were caused by epilepsy, not that they could be the cause."

In the study, Nedergaard and colleagues showed that astrocytes actually generate seizure activity, and the team linked astrocytes to a brain chemical long 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.

Then the team tested medications currently used to treat the disease. Epilepsy describes a condition in the brain where neurons start firing wildly and uncontrollably, sometimes resulting in seizures, and most medications aim to reduce such firing. The team showed that agents like gabapentin and valproate reduced the type of chemical signaling that causes astrocytes to release glutamate.

According to Nedergaard, many scientists have thought that epilepsy occurs when neurons that normally inhibit or slow down other neurons lose their power, as if the brakes on a speeding car were faulty. Current medications are aimed at making those molecular "brakes" more powerful and reining signals back in. But such drugs have side effects like drowsiness. Her work opens up a new avenue to understand the disease.

"The potential role of astrocytes in the generation of epilepsy has been largely ignored," says Michel Berg, M.D., medical director of the Strong Epilepsy Center. "Epilepsy involves a re-organization of the brain's pathways, in a way that is not completely understood, that results in recurrent seizures. Currently we have drugs to treat seizures, but not to prevent the whole process. Perhaps someday there will be ways to intervene before the circuitry is re-written, to prevent epilepsy completely."

More than 2 million Americans have epilepsy. Current medications stop seizures in about two-thirds of patients, but others often struggle for years or even a lifetime to cope with symptoms including seizures. Surgery to remove a small amount of troublesome brain tissue is often successful in such cases. The disease can come about as a result of a brain injury or because of genetic abnormalities in the way the brain develops.
 

- August 14 in Nature Medicine
 

University of Rochester Medical Center

 
Subscribe to Epilepsy Newsletter
E-mail Address:

 

In addition to Nedergaard, the team from the University's Department of Neurosurgery included Guo-Feng Tian and Weiguo Peng, research assistant professors; post-doctoral associates Takahiro Takano and Nanhong Lou; technical associate Qiwu Xu; and graduate student Nancy Ann Oberheim. Other authors include neurosurgeon Hooman Azmi from the New Jersey Medical School; Jane Lin and Jian Kang of New York Medical College in Valhalla; and Ron Zielke of the University of Maryland.

Related Epilepsy News

Responsive Neurostimulator System: An implantable device to treat epilepsy
Defibrillator to prevent epileptic seizures?
Septum sets the tempo of brain's electrical activity
Multiple-stage surgery brings hope for Tuberous Sclerosis with intractable seizures
Flexible Drug Dosing in Epilepsy Reduces Side Effects
Depression and anxiety improve after epilepsy surgery
Ketogenic diet prevents seizures
Blood Test Can Help Determine Type of Seizure
Propofol is effective in pediatric refractory status epilepticus
Astrocytes appear to play a key role in development of epilepsy


For any corrections of factual information, to contact the editors or to send any medical news or health news press releases, use feedback form

Top of Page

 

© Copyright 2004 onwards by RxPG Medical Solutions Private Limited
Contact Us