Featured Research

from universities, journals, and other organizations

Prenatal Exposure To Marine Toxin Causes Lasting Damage

Date:
September 8, 2005
Source:
Duke University Medical Center
Summary:
Duke University Medical Center researchers have found that the naturally occurring marine toxin domoic acid can cause subtle but lasting cognitive damage in rats exposed to the chemical before birth.

The researchers saw behavioral effects of the toxin in animals after prenatal exposure to domoic acid levels below those generally deemed safe for adults, said Edward Levin, Ph.D. Those effects –- including an increased susceptibility to disruptions of memory -- persisted into adulthood, he said.

The findings in rats, therefore, imply that the toxin might negatively affect unborn children at levels that do not cause symptoms in expectant mothers, said Levin. While the researchers note that eating seafood offers significant health benefits, they said their findings suggest that the current threshold of toxin at which affected fisheries are closed should perhaps be lowered. The Federal Drug Administration (FDA) set the current limit based on levels safe for adults, Levin said.

"A single administration of domoic acid to pregnant rats had a lasting affect on the performance of their offspring as adults," Levin said. "The consequences are life-long.

"The findings suggest we may need to re-evaluate monitoring of waters, shellfish and fish to make sure that the most sensitive parts of the human population are protected from toxic exposure to domoic acid," he continued.

The researchers reported their findings in a forthcoming special issue dedicated to research on marine toxins of Neurotoxicology and Teratology.

In 1987, more than 100 people in Canada became ill after eating cultured mussels contaminated with domoic acid. The incident led to three deaths and memory loss in several others.

First detected in the U.S. on the Washington coast in 1991, domoic acid is produced by microscopic algae, specifically the diatom species called Pseudo-nitzschia. When shellfish and crabs ingest the algae, the toxin can become concentrated in their bodies.

Humans eating contaminated seafood develop symptoms including vomiting nausea, diarrhea and abdominal cramps. In severe cases, the toxin leads to neurological damage, characterized by headaches, confusion, coma and even death. Exposure can also cause amnesic shellfish poisoning, characterized by permanent loss of short-term memory.

Since the discovery of domoic acid on the West Coast, officials there collect regular samples of affected marine animals, including razor clams and Dungeness crabs. Fisheries are closed when domoic acid levels reach 20 parts per million (ppm) in the animals' tissues, the level at which the FDA deems the toxin unsafe for human consumption.

Earlier studies in animals have focused on lethal and highly toxic doses of domoic acid. Such exposures cause extensive damage to the hippocampus, a part of the brain involved in learning and memory. More recent reports examining the effects of a range of doses have found highly reproducible behavioral consequences of sublethal doses of the marine toxin, including impairments to spatial memory.

To explore the toxin's effects during development, the Duke team administered domoic acid to pregnant rats at three levels -- each below those found to cause convulsions or fetal loss. Others animals did not receive the toxin. The researchers then conducted a battery of behavioral tests on the exposed and normal animals to determine the effects of early domoic acid on movement and working memory.

Rats with a history of domoic acid exposure showed greater initial activity in a maze test than control rats, followed by a rapid decline. Moreover, domoic acid exposure affected cognitive function in complex ways, the researchers reported.

Toxin exposure decreased the normal difference between male and female rats in their ability to complete tasks of spatial memory, the researchers found. Previous research has shown that males normally outperform females on spatial discrimination learning in particular maze tests.

Exposed rats of both sexes also showed greater susceptibility to a chemical that induces amnesia by compromising particular brain receptors, suggesting that the animals had less functional reserve with which to solve memory tasks, the researchers said.

"Brief, low-dose domoic acid exposure in rats during gestational development results in subtle neurobehavioral impairments that persist into adolescence and adulthood," Levin said. "Furthermore, long-lasting effects on locomotor activity and cognitive function occurred at levels having no clinically evident consequences for the animals."

Collaborators on the study include Kristen Pizarro, Wyki Gina Pang and Jerry Harrison, all of Duke. John Ramsdell of the NOAA-National Ocean Service also contributed to the research.


Story Source:

The above story is based on materials provided by Duke University Medical Center. Note: Materials may be edited for content and length.


Cite This Page:

Duke University Medical Center. "Prenatal Exposure To Marine Toxin Causes Lasting Damage." ScienceDaily. ScienceDaily, 8 September 2005. <www.sciencedaily.com/releases/2005/09/050908084539.htm>.
Duke University Medical Center. (2005, September 8). Prenatal Exposure To Marine Toxin Causes Lasting Damage. ScienceDaily. Retrieved April 18, 2014 from www.sciencedaily.com/releases/2005/09/050908084539.htm
Duke University Medical Center. "Prenatal Exposure To Marine Toxin Causes Lasting Damage." ScienceDaily. www.sciencedaily.com/releases/2005/09/050908084539.htm (accessed April 18, 2014).

Share This



More Health & Medicine News

Friday, April 18, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

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
Is Apathy A Sign Of A Shrinking Brain?

Is Apathy A Sign Of A Shrinking Brain?

Newsy (Apr. 17, 2014) A recent study links apathetic feelings to a smaller brain. Researchers say the results indicate a need for apathy screening for at-risk seniors. Video provided by Newsy
Powered by NewsLook.com
Could Even Casual Marijuana Use Alter Your Brain?

Could Even Casual Marijuana Use Alter Your Brain?

Newsy (Apr. 16, 2014) A new study conducted by researchers at Northwestern and Harvard suggests even casual marijuana use can alter your brain. Video provided by Newsy
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