title: Azaspiracid-1 inhibits bioelectrical activity of spinal cord neuronal networks.
abstract: Azaspiracid-1 (AZA-1) is a recently identified phycotoxin that accumulates in molluscs and can cause severe human intoxications. For this study, we utilized murine spinal cord and frontal cortex neuronal networks grown over 64 channel microelectrode arrays (MEAs) to gain insights into the mechanism of action of AZA-1 on neuronal cells. Extracellular recordings of spontaneous action potentials were performed by monitoring mean spike rate as an assay of the efficacy of AZA-1 to alter the bioelectrical activity of neurons in the networks. Via slow onset, AZA-1 decreased the mean spike rate of the spinal cord neurons with an IC(50) of ca. 2.1nM, followed by partial recovery of original activity when toxin was removed. Pre-treatment with the GABA(A) receptor antagonist bicuculline led to an increased response of the neuronal networks to AZA-1 exposure and resulted in an irreversible inhibition of spike rate. AZA-1 did not cause any changes in frontal cortex networks upon drug exposure. In addition, whole-cell patch clamp recordings from spinal cord neurons showed that AZA-1 had no significant effect on the voltage-gated sodium (Na(+)) or calcium (Ca(2+)) currents, suggesting that the toxin affected synaptic transmission in the neuronal networks through a mechanism independent of these voltage-gated channels.
authors.affiliation: Center for Bio/Molecular Science and Engineering, Naval Research Laboratory, 4555 Overlook Avenue SW, Code 6900, Washington, DC 20375, USA. kulagina@cbmse.nrl.navy.mil
authors.forename: Nadezhda V
authors.initials: NV
authors.lastname: Kulagina
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Twiner
authors.forename: Philipp
authors.initials: P
authors.lastname: Hess
authors.forename: Terry
authors.initials: T
authors.lastname: McMahon
authors.forename: Masayuki
authors.initials: M
authors.lastname: Satake
authors.forename: Takeshi
authors.initials: T
authors.lastname: Yasumoto
authors.forename: John S
authors.initials: JS
authors.lastname: Ramsdell
authors.forename: Gregory J
authors.initials: GJ
authors.lastname: Doucette
authors.forename: Wu
authors.initials: W
authors.lastname: Ma
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: O'Shaughnessy
mesh_terms: D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D002118:Calcium / Q000378:metabolism; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D004553:Electric Conductivity; D008387:Marine Toxins / Q000494:pharmacology*; D051379:Mice; D009415:Nerve Net / Q000187:drug effects* / Q000502:physiology*; D009474:Neurons / Q000187:drug effects* / Q000502:physiology; D012964:Sodium / Q000378:metabolism; D013116:Spinal Cord / Q000166:cytology* / Q000187:drug effects* / Q000378:metabolism; D013141:Spiro Compounds / Q000494:pharmacology*; D000095702:Polyether Toxins
chemical_list: D002118:Calcium; D008387:Marine Toxins; D012964:Sodium; D013141:Spiro Compounds; C406592:azaspiracid; D000095702:Polyether Toxins