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Algae Toxin Traced Through Rat Brains Yields Clues to Sea Lion Seizure Risk

To better understand epileptic disease caused by an algal toxin in young California sea lions, researchers from the National Centers for Coastal Ocean Science exposed pregnant lab rats to the substance and studied its movement. In the adult rats, the toxin—known as domoic acid—enters the brain and surrounding fluid quickly and exits from the cerebrospinal fluid just as fast, protecting them from long-term harm. The fetuses did not fare as well. The toxins in their brains lingered much longer, which can lead to greater risk of severe neurological damage.

Epilepsy is a condition that produces seizures affecting a variety of mental and physical functions. It is also called a seizure disorder. Seizures happen when clusters of nerve cells in the brain signal abnormally, which may briefly alter consciousness, movements or actions, according to the Epilepsy Foundation’s website.

An earlier study conducted by NCCOS scientists identified the link between aggressive behaviors and epileptic symptoms in adult sea lions after eating fish contaminated with this toxin, which is produced by a common ocean algae.

Domoic acid transfers easily from blood plasma into the brain and its interstitial fluid, as well as cerebrospinal fluid.

Domoic acid transfers easily from blood plasma into the brain and its interstitial fluid, as well as cerebrospinal fluid.

The pregnant rat model model, along with others, was developed by scientists in the Harmful Algal Bloom and Analytical Research group of NCCOS to better understand the epileptic disease seen in young California sea lions and how it may originate with exposure to domoic acid in utero.

The pregnant sea lions feed on prey that have accumulated the toxin, which is produced by the diatom Pseudo-nitzschia spp., and the toxin is then transferred to the developing fetuses. Knowing how long the DA stays in the brains and fluids of both the mother and fetuses will help to fully understand how much toxin these prenatal sea lions are being exposed to and if it is enough to cause the epileptic disease seen in juveniles.

domoic acid transfer rate from blood to brain to cerebrospinal fluid

Graph of the rate of domoic acid transfer from plasma to brain and from the brain to the cerebrospinal fluid

Read the manuscript: Elimination kinetics of domoic acid from the brain and cerebrospinal fluid of the pregnant rat

Related research article: Toxicokinetics of domoic acid in the fetal rat

2008 Science Daily article: Toxic Algal Blooms May Cause Seizures in California Sea Lions

usoceangov Ocean Today kiosk video: Sea Lion Sickness

Fact sheet: Pseudo-nitzschia spp.

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Shorter web link for sharing: http://coastalscience.noaa.gov/news/?p=8352

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