title: Domoic acid disrupts the activity and connectivity of neuronal networks in organotypic brain slice cultures.
abstract: Domoic acid is a neurotoxin produced by algae and is found in seafood during harmful algal blooms. As a glutamate agonist, domoic acid inappropriately stimulates excitatory activity in neurons. At high doses, this leads to seizures and brain lesions, but it is unclear how lower, asymptomatic exposures disrupt neuronal activity. Domoic acid has been detected in an increasing variety of species across a greater geographical range than ever before, making it critical to understand the potential health impacts of low-level exposure on vulnerable marine mammal and human populations. To determine whether prolonged domoic acid exposure altered neuronal activity in hippocampal networks, we used a custom-made 512 multi-electrode array with high spatial and temporal resolution to record extracellular potentials (spikes) in mouse organotypic brain slice cultures. We identified individual neurons based on spike waveform and location, and measured the activity and functional connectivity within the neuronal networks of brain slice cultures. Domoic acid exposure significantly altered neuronal spiking activity patterns, and increased functional connectivity within exposed cultures, in the absence of overt cellular or neuronal toxicity. While the overall spiking activity of neurons in domoic acid-exposed cultures was comparable to controls, exposed neurons spiked significantly more often in bursts. We also identified a subset of neurons that were electrophysiologically silenced in exposed cultures, and putatively identified those neurons as fast-spiking inhibitory neurons. These results provide evidence that domoic acid affects neuronal activity in the absence of cytotoxicity, and suggest that neurodevelopmental exposure to domoic acid may alter neurological function in the absence of clinical symptoms.
authors: Department of Microbiology & Environmental Toxicology, University of California, Santa Cruz, CA, USA.
authors: E M
authors: EM
authors: Hiolski
authors: Santa Cruz Institute for Particle Physics, University of California, Santa Cruz, CA, USA.
authors: S
authors: S
authors: Ito
authors: Department of Physics, Indiana University, Bloomington, IN, USA.
authors: J M
authors: JM
authors: Beggs
authors: Northwest Fisheries Science Center, NOAA Fisheries, Seattle, WA, USA.
authors: K A
authors: KA
authors: Lefebvre
authors: Santa Cruz Institute for Particle Physics, University of California, Santa Cruz, CA, USA.
authors: A M
authors: AM
authors: Litke
authors: Department of Microbiology & Environmental Toxicology, University of California, Santa Cruz, CA, USA.
authors: D R
authors: DR
authors: Smith
mesh_terms: D000200:Action Potentials / Q000187:drug effects*; D000465:Algorithms; D000818:Animals; D000831:Animals, Newborn; D002452:Cell Count; D004305:Dose-Response Relationship, Drug; D019277:Entropy; D006624:Hippocampus / Q000187:drug effects*; D066298:In Vitro Techniques; D007608:Kainic Acid / Q000031:analogs & derivatives* / Q000494:pharmacology; D051379:Mice; D009415:Nerve Net / Q000187:drug effects*; D009498:Neurotoxins / Q000494:pharmacology*; D009924:Organ Culture Techniques; D010751:Phosphopyruvate Hydratase / Q000378:metabolism
chemical_list: D009498:Neurotoxins; D010751:Phosphopyruvate Hydratase; C012301:domoic acid; D007608:Kainic Acid
keywords: Developmental neurotoxicity; Domoic acid; Multielectrode recording; Organotypic brain slice culture