Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Prenatal Exposure to Marine Toxin Causes Lasting Damage

07.09.2005


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. Humans can become poisoned by the potentially lethal, algal toxin after eating contaminated shellfish.



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.

Kendall Morgan | EurekAlert!
Further information:
http://www.duke.edu

More articles from Life Sciences:

nachricht Researchers identify potentially druggable mutant p53 proteins that promote cancer growth
09.12.2016 | Cold Spring Harbor Laboratory

nachricht Plant-based substance boosts eyelash growth
09.12.2016 | Fraunhofer-Institut für Angewandte Polymerforschung IAP

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Electron highway inside crystal

Physicists of the University of Würzburg have made an astonishing discovery in a specific type of topological insulators. The effect is due to the structure of the materials used. The researchers have now published their work in the journal Science.

Topological insulators are currently the hot topic in physics according to the newspaper Neue Zürcher Zeitung. Only a few weeks ago, their importance was...

Im Focus: Significantly more productivity in USP lasers

In recent years, lasers with ultrashort pulses (USP) down to the femtosecond range have become established on an industrial scale. They could advance some applications with the much-lauded “cold ablation” – if that meant they would then achieve more throughput. A new generation of process engineering that will address this issue in particular will be discussed at the “4th UKP Workshop – Ultrafast Laser Technology” in April 2017.

Even back in the 1990s, scientists were comparing materials processing with nanosecond, picosecond and femtosesecond pulses. The result was surprising:...

Im Focus: Shape matters when light meets atom

Mapping the interaction of a single atom with a single photon may inform design of quantum devices

Have you ever wondered how you see the world? Vision is about photons of light, which are packets of energy, interacting with the atoms or molecules in what...

Im Focus: Novel silicon etching technique crafts 3-D gradient refractive index micro-optics

A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.

Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...

Im Focus: Quantum Particles Form Droplets

In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.

“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ICTM Conference 2017: Production technology for turbomachine manufacturing of the future

16.11.2016 | Event News

Innovation Day Laser Technology – Laser Additive Manufacturing

01.11.2016 | Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

 
Latest News

Researchers identify potentially druggable mutant p53 proteins that promote cancer growth

09.12.2016 | Life Sciences

Scientists produce a new roadmap for guiding development & conservation in the Amazon

09.12.2016 | Ecology, The Environment and Conservation

Satellites, airport visibility readings shed light on troops' exposure to air pollution

09.12.2016 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>