Featured Research

from universities, journals, and other organizations

Some Mysteries Of Neonatal Seizures Explained

Date:
September 9, 2009
Source:
Massachusetts General Hospital
Summary:
A new study provides new insight into the mechanism of neonatal seizures, which have features very different from seizures in older children and adults. The finding that neurons in different parts of the brains of newborn mammals respond differently to the neurotransmitter GABA may explain why seizures in the neonatal brain may not produce visible convulsions and why the antiseizure drug phenobarbital can exacerbate the invisible nature of neonatal seizures.

A study led by MassGeneral Hospital for Children (MGHfC) investigators is providing new insight into the mechanism of neonatal seizures, which have features very different from seizures in older children and adults. In their report in the Sept. 10 issue of Neuron, the researchers describe finding how neurons in different parts of the brains of newborn mammals respond differently to the neurotransmitter GABA, an observation that may explain why seizure activity in the neonatal brain often does not produce visible convulsions and why the common antiseizure drug phenobarbital can exacerbate the invisible nature of neonatal seizures.

"The incidence of seizures is higher in the newborn period than at any other stage of life," says Kevin Staley, MD, MGHfC chief of Neurology, senior author of the Neuron paper. "This is a time of transition when brain cells begin to switch the way they respond to the neurotransmitter GABA, which increases the activity of immature brain cells but decreases the activity of mature cells. Many of our most powerful seizure medicines work by enhancing the action of GABA, but this treatment may backfire for brain cells that have not yet made that transition."

GABA acts by mediating the flow of chloride ions into and out of neurons, and previous research has shown that neurons in structures deep within the developing mammalian brain change the expression of proteins that pump ions in or out of cells at an earlier stage than do neurons in the neocortex, the outer part of the brain that matures last and where seizures originate. The current study was designed to investigate whether the different expression of chloride pumps in specific regions of the brain might explain why newborns often have seizures not accompanied by convulsions.

The researchers first confirmed in newborn mice that chloride levels in deep-brain structures like the thalamus are much lower than cortical levels, a difference that decreases as the animals mature and cortical chloride levels drop. They then showed that GABA inhibits the activity of thalamic neurons but stimulates cortical neurons in neonatal rats, a difference that was enhanced by the induction of seizures.

Treatment with phenobarbital suppressed seizure activity in subcortical structures but not in the neocortex. That finding could explain the suppression of convulsions, which require the passage of seizure signals from the cortex through subcortical structures and out to the muscles, while a cortical seizure persists. Adding the diuretic bumetanide, which blocks the chloride pump responsible for immature neurons' excitatory response to GABA, to phenobarbital treatment successfully suppressed seizure activity in both cortical and subcortical regions.

"Our study provides a logical mechanism for the clinical invisibility of many neonatal seizures, information that may help determine the best way to monitor newborns with brain injuries for seizures and select the best strategies for anticonvulsant treatment," Staley explains. "For example, by blocking the protein responsible for immature brain cells' excitatory response to GABA, bumetanide essentially converts that immature response to a mature response and allows antiseizure medicines to work properly. We are excited to be participating in a trial of bumetanide as an adjunctive treatment of neonatal seizures currently being carried out in collaboration with colleagues at Childrens Hospital Boston and Brigham and Women's Hospital."

Staley is the Joseph P. and Rose F. Kennedy Professor of Neurology at Harvard Medical School. Co-first authors of the Neuron paper are Joseph Glykys, MD, PhD, MGHfC, and Volodymyr Dzhala, PhD, MassGeneral Institute for Neurodegenerative Disease (MIND). Additional co-authors are Kishore Kuchibhotla and Brian Bacskai, PhD, MIND; Guoping Fang, PhD, and George Augustine, PhD, Duke University; and Thoma Kuner, PhD, University of Heidelberg, Germany. The study was supported by grants from the National Institute of Health and the Epilepsy Foundation.


Story Source:

The above story is based on materials provided by Massachusetts General Hospital. Note: Materials may be edited for content and length.


Cite This Page:

Massachusetts General Hospital. "Some Mysteries Of Neonatal Seizures Explained." ScienceDaily. ScienceDaily, 9 September 2009. <www.sciencedaily.com/releases/2009/09/090909122058.htm>.
Massachusetts General Hospital. (2009, September 9). Some Mysteries Of Neonatal Seizures Explained. ScienceDaily. Retrieved April 19, 2014 from www.sciencedaily.com/releases/2009/09/090909122058.htm
Massachusetts General Hospital. "Some Mysteries Of Neonatal Seizures Explained." ScienceDaily. www.sciencedaily.com/releases/2009/09/090909122058.htm (accessed April 19, 2014).

Share This



More Health & Medicine News

Saturday, April 19, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

'Holy Grail' Of Weight Loss? New Find Could Be It

'Holy Grail' Of Weight Loss? New Find Could Be It

Newsy (Apr. 18, 2014) In a potential breakthrough for future obesity treatments, scientists have used MRI scans to pinpoint brown fat in a living adult for the first time. Video provided by Newsy
Powered by NewsLook.com
Little Progress Made In Fighting Food Poisoning, CDC Says

Little Progress Made In Fighting Food Poisoning, CDC Says

Newsy (Apr. 18, 2014) A new report shows rates of two foodborne infections increased in the U.S. in recent years, while salmonella actually dropped 9 percent. Video provided by Newsy
Powered by NewsLook.com
Scientists Create Stem Cells From Adult Skin Cells

Scientists Create Stem Cells From Adult Skin Cells

Newsy (Apr. 17, 2014) The breakthrough could mean a cure for some serious diseases and even the possibility of human cloning, but it's all still a way off. Video provided by Newsy
Powered by NewsLook.com
Obama: 8 Million Healthcare Signups

Obama: 8 Million Healthcare Signups

AP (Apr. 17, 2014) President Barack Obama gave a briefing Thursday announcing 8 million people have signed up under the Affordable Care Act. He blasted continued Republican efforts to repeal the law. (April 17) Video provided by AP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins