Domoic acid from toxic algal blooms may cause seizures in California sea lions

June 09, 2008

Scientists, reporting in the current issue of the online journal Marine Drugs, state that an increase of epileptic seizures and behavioral abnormalities in California sea lions can result from low-dose exposure to domoic acid as a fetus. The findings follow an analysis earlier this year led by Frances Gulland of the California Marine Mammal Center that showed this brain disturbance to be a newly recognized chronic disease.

John Ramsdell of NOAA's Center for Environmental Health and Biomolecular Research in Charleston, SC, in partnership with Tanja Zabka, a veterinary pathologist at the Marine Mammal Center, conducted the first-of-its kind analysis of poisoning by the algal toxin, domoic acid, during fetal brain development. The results, analyzed across multiple animal species, point to the toxin as a cause for behavioral changes and epilepsy that does not become evident until later in life.

Domoic acid is produced by harmful algal blooms. The algae is consumed by fish such as sardines, herring and anchovies, a significant part of the sea lion diet. Exposure during pregnancy concentrates the domoic acid toxin in the mother's amniotic fluid, which normally protects and aids in the growth of a fetus. In sea lions exposed to domoic acid, the fluid retains the toxin, thus subjecting the fetus to repeated direct absorption through immature skin cells and swallowing during gestation.

The results, demonstrated experimentally in laboratory animals and projected to occur in fetal sea lions, is abnormal development of brain neurons which does not impact the animal until it enters later life stages. This phenomenon, known as "fetal basis to adult disease," is expressed through seizures and abnormal behavioral changes.

"This represents a significant break through in understanding the origins of this behavior and will help us better understand the long-term consequences of exposure to harmful algal blooms during pregnancy," notes Ramsdell.

Algal blooms have been increasing in the sea lions' habitat, resulting in more cases of acute poisoning and increased concern over the long-term effects of algal toxins.

Scientists in NOAA's Oceans and Human Health Initiative are studying the impact of harmful algal blooms on marine mammals to determine if similar impacts could affect humans exposed to the similar harmful toxins.
-end-
The National Oceanic and Atmospheric Administration, an agency of the U.S. Commerce Department, is dedicated to enhancing economic security and national safety through the prediction and research of weather and climate-related events and information service delivery for transportation, and by providing environmental stewardship of our nation's coastal and marine resources. Through the emerging Global Earth Observation System of Systems (GEOSS), NOAA is working with its federal partners, more than 70 countries and the European Commission to develop a global monitoring network that is as integrated as the planet it observes, predicts and protects.

On the Web:
NOAA: http://www.noaa.gov
Marine Drugs Journal: http://www.mdpi.org/marinedrugs

NOAA Headquarters

Related Seizures Articles from Brightsurf:

Hallucinations in people with seizures may point to suicide risk
A study from scientists at Trinity College Dublin and Royal College of Surgeons in Ireland shows that 8% of individuals with a history of seizures report hallucinations, including experiences of hearing or seeing things that are not based in reality.

Epilepsy: Seizures not forecastable as expected
Epileptic seizures can probably not be predicted by changes in brain wave patterns that were previously assumed to be characteristic precursors.

Predicting epileptic seizures might be more difficult than previously thought
By studying the brain dynamics of 28 subjects with epilepsy, scientists demonstrated there is no evidence for a previously suspected warning sign for seizures known as 'critical slowing down,' which refers to characteristic changes in the behavior of a complex system that approaches a theoretical tipping point; when this point is exceeded, there can be impactful and devastating changes.

Gene protective against fruit fly heat-induced seizures may explain some human seizures
Researchers identified a gene in fruit flies that helps prevent the hyperexcitability of specific neurons that trigger seizures.

Rethinking seizures associated with cardiac disease
Research from Washington University in St. Louis finds that mutations of a gene implicated in long QT syndrome in humans may trigger seizures because of their direct effects on certain classes of neurons in the brain -- independent from what the genetic mutations do to heart function.

UTSA reduces seizures by removing newborn neurons
Epileptic seizures happen in one of every 10 people who have experienced a traumatic brain injury (TBI).

Reducing seizures by removing newborn neurons
Removing new neurons born after a brain injury reduces seizures in mice, according to new research in JNeurosci.

Inducing seizures to stop seizures
Surgery is the only way to stop seizures in 30 per cent of patients with focal drug-resistant epilepsy.

New research could help predict seizures before they happen
A new study has found a pattern of molecules that appear in the blood before a seizure happens.

New drug could help treat neonatal seizures
A new drug that inhibits neonatal seizures in rodent models could open up new avenues for the treatment of epilepsy in human newborns.

Read More: Seizures News and Seizures Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.