Excitotoxicity of Domoic Acid: A Possible
Epidemic

ABSTRACT:
With increasing changes in the environment, harmful algal blooms are occurring at a more frequent rate within ocean waters. One particularly harmful bloom arising in more frequent numbers is domoic acid which comes from the algae Pseudo-nitzschia australis. Domoic acid works in a similar fashion as glutamatergic excitotoxicity and can cause detrimental effects to the organisms that it affects. These excitotoxic effects seem to target AMPA and kainate receptors causing mild to severe deficits to the central nervous system as well as the autonomic nervous system. Further studies show that the effects of domoic acid can cause behavioral deficits as well as gastrointestinal problems concurrently with nervous system problems. As more research is being done, studies are showing that domoic acid can be used as a possible model for temporal lobe epilepsy because it has similar a similar pathology and symptomology as the disorder. These studies along with studies showing the effects of domoic acid on prenatal development give rise to the idea that domoic acid could potentially be a causative environmental agent for the development of temporal lobe epilepsy. Overall, the effects of domoic acid range from mild to severe health consequences and can ultimately cause death in organisms that are affected. Until more is understood about the molecule and treatments are found individuals should be aware of potential health risks that could originate from the consumption of contaminated seafood.

From some of the earliest records in history, humans have been reliant on ocean waters for trade, commerce, communication, and more importantly, as a source of food. With around seventy percent of the Earth’s surface covered in water it is not surprising that humans have looked toward the ocean as a source of nourishment. As of 2010, over three billion people in the world rely on ocean and marine organisms as a primary source of food and that number is swiftly escalating. (Save the Sea 2011) As the consumption of marine organisms increases, more studies are being done in order ensure that chemicals found in the ocean do not have any harmful side effects after being ingested. Since the late fifties, researchers have strived to create a link between a particular marine chemical that has had a devastating impact on many wildlife species, as well as humans. This chemical, domoic acid, was first discovered and described as a component of “domoi,” a Japanese folk medicine, in 1958, but it was not until the late eighties and early nineties that a link between this chemical and its harmful effects on wildlife were shown. (Grant et al. 2010; Silvagni et al. 2005) Before this connection was found, many researchers were curious as to what could possibly be causing fish-eating seabirds, sea lions, and even humans to suffer from mild to serious health problems after consuming different types of food; the answer was, of course, domoic acid. As further research is being done, domoic acid has been shown to have detrimental effects on the central nervous system of mammals. (Silvagni et al. 2005) These effects on the central nervous system work in a similar fashion as the excitotoxicity of glutamatergic synapses and can yield severe neurological problems and even death in the organisms that it affects. Domoic acid is one of many marine biotoxins that arise from harmful algal blooms. The most common algae that has been associated with domoic acid is Pseudo-nitzschia australis, which is a colorless bloom that is becoming more and more frequent off the coastlines of many countries. The occurrence of these blooms in the water is especially high during the late spring and summer months due to the increasing rainfall and nutrients within the seawater. (Jeffrey et al. 2004) The concentration of these harmful blooms within coastal waters occurs when local water conditions