Accession Number : ADA271224


Title :   Brevetoxin Depresses Synaptic Transmission in Guinea Pig Hippocampal Slices


Corporate Author : ARMY MEDICAL RESEARCH INST OF CHEMICAL DEFENSE ABERDEEN PROVING GROUND MD


Personal Author(s) : Apland, J P ; Adler, M ; Sheridan, R E


Full Text : https://apps.dtic.mil/dtic/tr/fulltext/u2/a271224.pdf


Report Date : Jan 1993


Pagination or Media Count : 8


Abstract : Brevetoxin depresses synaptic transmission in guinea pig hippocampal slices. Brain Res Bull 31(1/2) 201-207, 1993.--Extracellular recordings were obtained from area CA1 of guinea pig hippocampal slices. PbTx-3, a brevetoxin fraction isolated from the red tide dinoflagellate Ptychodiscus brevis, was applied by bath perfusion. The toxin produced a concentration-dependent depression of the orthodromically evoked population spike with an EC50 of 37.5 nM. Brevetoxin concentrations below 10 nM were without effect, and concentrations above 100 nM led to total inhibition of evoked responses. PbTx-3 did not produce spontaneous synchronous discharges but did induce after- discharges following evoked responses in about 50% of the slices tested, particularly at concentrations between 10 nM and 100 nM. Orthodromically evoked responses were more sensitive to PbTx-3 than were those elicited by antidromic stimulation. High-Ca2+ solution, 4-aminopyridine, and tetraethylammonium failed to antagonize either orthodromic or antidromic effects of the toxin. Although the precise mechanism by which PbTx-3 depresses evoked responses is not certain, depolarization of the presynaptic nerve terminals leading to failure of transmitter release could explain the toxin's actions. This is the first report of the effects of brevetoxin applied directly to central nervous system tissue.


Descriptors :   *SYNAPSE , *HIPPOCAMPUS , *NEUROPHYSIOLOGY , REPRINTS , SODIUM , ELECTROPHYSIOLOGY , CENTRAL NERVOUS SYSTEM , AMINO ACIDS , CHANNELS , NEUROTRANSMITTERS


Subject Categories : Anatomy and Physiology


Distribution Statement : APPROVED FOR PUBLIC RELEASE