Brevetoxin-induced autocrine excitotoxicity is associated with manifold routes of Ca2+ influx

Frederick W. Berman, Thomas F. Murray

Research output: Contribution to journalArticle

50 Citations (Scopus)

Abstract

Real-time alterations in intracellular Ca2+ ([Ca2+](i)) were monitored in fluo-3-loaded cerebellar granule neurons (CGNs) exposed to the brevetoxin PbTx-1. [Ca2+](i) was measured using a fluorescent plate reader (FLIPR), which measures simultaneously the mean intracellular Ca2+ change in a population of cultured cells in each well of a 96-well plate. PbTx-1 produced rapid and concentration-dependent increases in neuronal [Ca2+](i) with a potency nearly identical to that determined previously for PbTx-1- induced neurotoxicity. The NMDA receptor antagonists MK-801, dextrorphan, and D(-)-2-amino-5-phosphonopentanoic acid, and tetanus toxin, an inhibitor of Ca2+dependent exocytotic neurotransmitter release, effected significant reductions in both the integrated fluo-3 fluorescence response and excitatory amino acid release and protected CGNs against PbTx-1 neurotoxicity. The L- type Ca2+ channel antagonist nifedipine produced a modest reduction in the fluo-3 response but reduced substantially the plateau phase of the PbTx-1 increment in [Ca2+](i) when combined with MK-801. When nifedipine and MK- 801 were combined with the Na+/Ca2+ exchanger (reversed mode) inhibitor KB-R7943, the PbTx-1 increment in [Ca2+](i) was nearly completely attenuated. These data show that Ca2+ entry into PbTx-1-exposed CGNs occurs through three primary routes: NMDA receptor ion channels, L-type Ca2+ channels, and reversal of the Na+/Ca2+ exchanger. There was a close correlation between reduction of the integrated fluo-3 fluorescence response and the level of neuroprotection afforded by blockers of each Ca2+ entry pathway; however, simultaneous blockade of L-type Ca2+ channels and the Na+/Ca2+ exchanger, although reducing the integrated [Ca2+](i) response to a level below that provided by NMDA receptor blockade alone, failed to completely attenuate PbTx-1 neurotoxicity. This finding suggests that in addition to total [Ca2+](i) load, neuronal vulnerability is governed principally by the NMDA receptor Ca2+ influx pathway.

Original languageEnglish
Pages (from-to)1443-1451
Number of pages9
JournalJournal of Neurochemistry
Volume74
Issue number4
DOIs
StatePublished - 2000
Externally publishedYes

Fingerprint

N-Methyl-D-Aspartate Receptors
Dizocilpine Maleate
Neurons
Nifedipine
Dextrorphan
Fluorescence
2-Amino-5-phosphonovalerate
Tetanus Toxin
Excitatory Amino Acids
Ion exchangers
Ion Channels
Neurotransmitter Agents
Cultured Cells
Cells
Fluo-3
brevetoxin
Population

All Science Journal Classification (ASJC) codes

  • Biochemistry
  • Cellular and Molecular Neuroscience

Cite this

Brevetoxin-induced autocrine excitotoxicity is associated with manifold routes of Ca2+ influx. / Berman, Frederick W.; Murray, Thomas F.

In: Journal of Neurochemistry, Vol. 74, No. 4, 2000, p. 1443-1451.

Research output: Contribution to journalArticle

@article{90a79f8838974937b2fb8322238dd321,
title = "Brevetoxin-induced autocrine excitotoxicity is associated with manifold routes of Ca2+ influx",
abstract = "Real-time alterations in intracellular Ca2+ ([Ca2+](i)) were monitored in fluo-3-loaded cerebellar granule neurons (CGNs) exposed to the brevetoxin PbTx-1. [Ca2+](i) was measured using a fluorescent plate reader (FLIPR), which measures simultaneously the mean intracellular Ca2+ change in a population of cultured cells in each well of a 96-well plate. PbTx-1 produced rapid and concentration-dependent increases in neuronal [Ca2+](i) with a potency nearly identical to that determined previously for PbTx-1- induced neurotoxicity. The NMDA receptor antagonists MK-801, dextrorphan, and D(-)-2-amino-5-phosphonopentanoic acid, and tetanus toxin, an inhibitor of Ca2+dependent exocytotic neurotransmitter release, effected significant reductions in both the integrated fluo-3 fluorescence response and excitatory amino acid release and protected CGNs against PbTx-1 neurotoxicity. The L- type Ca2+ channel antagonist nifedipine produced a modest reduction in the fluo-3 response but reduced substantially the plateau phase of the PbTx-1 increment in [Ca2+](i) when combined with MK-801. When nifedipine and MK- 801 were combined with the Na+/Ca2+ exchanger (reversed mode) inhibitor KB-R7943, the PbTx-1 increment in [Ca2+](i) was nearly completely attenuated. These data show that Ca2+ entry into PbTx-1-exposed CGNs occurs through three primary routes: NMDA receptor ion channels, L-type Ca2+ channels, and reversal of the Na+/Ca2+ exchanger. There was a close correlation between reduction of the integrated fluo-3 fluorescence response and the level of neuroprotection afforded by blockers of each Ca2+ entry pathway; however, simultaneous blockade of L-type Ca2+ channels and the Na+/Ca2+ exchanger, although reducing the integrated [Ca2+](i) response to a level below that provided by NMDA receptor blockade alone, failed to completely attenuate PbTx-1 neurotoxicity. This finding suggests that in addition to total [Ca2+](i) load, neuronal vulnerability is governed principally by the NMDA receptor Ca2+ influx pathway.",
author = "Berman, {Frederick W.} and Murray, {Thomas F.}",
year = "2000",
doi = "10.1046/j.1471-4159.2000.0741443.x",
language = "English",
volume = "74",
pages = "1443--1451",
journal = "Journal of Neurochemistry",
issn = "0022-3042",
publisher = "Wiley-Blackwell",
number = "4",

}

TY - JOUR

T1 - Brevetoxin-induced autocrine excitotoxicity is associated with manifold routes of Ca2+ influx

AU - Berman, Frederick W.

AU - Murray, Thomas F.

PY - 2000

Y1 - 2000

N2 - Real-time alterations in intracellular Ca2+ ([Ca2+](i)) were monitored in fluo-3-loaded cerebellar granule neurons (CGNs) exposed to the brevetoxin PbTx-1. [Ca2+](i) was measured using a fluorescent plate reader (FLIPR), which measures simultaneously the mean intracellular Ca2+ change in a population of cultured cells in each well of a 96-well plate. PbTx-1 produced rapid and concentration-dependent increases in neuronal [Ca2+](i) with a potency nearly identical to that determined previously for PbTx-1- induced neurotoxicity. The NMDA receptor antagonists MK-801, dextrorphan, and D(-)-2-amino-5-phosphonopentanoic acid, and tetanus toxin, an inhibitor of Ca2+dependent exocytotic neurotransmitter release, effected significant reductions in both the integrated fluo-3 fluorescence response and excitatory amino acid release and protected CGNs against PbTx-1 neurotoxicity. The L- type Ca2+ channel antagonist nifedipine produced a modest reduction in the fluo-3 response but reduced substantially the plateau phase of the PbTx-1 increment in [Ca2+](i) when combined with MK-801. When nifedipine and MK- 801 were combined with the Na+/Ca2+ exchanger (reversed mode) inhibitor KB-R7943, the PbTx-1 increment in [Ca2+](i) was nearly completely attenuated. These data show that Ca2+ entry into PbTx-1-exposed CGNs occurs through three primary routes: NMDA receptor ion channels, L-type Ca2+ channels, and reversal of the Na+/Ca2+ exchanger. There was a close correlation between reduction of the integrated fluo-3 fluorescence response and the level of neuroprotection afforded by blockers of each Ca2+ entry pathway; however, simultaneous blockade of L-type Ca2+ channels and the Na+/Ca2+ exchanger, although reducing the integrated [Ca2+](i) response to a level below that provided by NMDA receptor blockade alone, failed to completely attenuate PbTx-1 neurotoxicity. This finding suggests that in addition to total [Ca2+](i) load, neuronal vulnerability is governed principally by the NMDA receptor Ca2+ influx pathway.

AB - Real-time alterations in intracellular Ca2+ ([Ca2+](i)) were monitored in fluo-3-loaded cerebellar granule neurons (CGNs) exposed to the brevetoxin PbTx-1. [Ca2+](i) was measured using a fluorescent plate reader (FLIPR), which measures simultaneously the mean intracellular Ca2+ change in a population of cultured cells in each well of a 96-well plate. PbTx-1 produced rapid and concentration-dependent increases in neuronal [Ca2+](i) with a potency nearly identical to that determined previously for PbTx-1- induced neurotoxicity. The NMDA receptor antagonists MK-801, dextrorphan, and D(-)-2-amino-5-phosphonopentanoic acid, and tetanus toxin, an inhibitor of Ca2+dependent exocytotic neurotransmitter release, effected significant reductions in both the integrated fluo-3 fluorescence response and excitatory amino acid release and protected CGNs against PbTx-1 neurotoxicity. The L- type Ca2+ channel antagonist nifedipine produced a modest reduction in the fluo-3 response but reduced substantially the plateau phase of the PbTx-1 increment in [Ca2+](i) when combined with MK-801. When nifedipine and MK- 801 were combined with the Na+/Ca2+ exchanger (reversed mode) inhibitor KB-R7943, the PbTx-1 increment in [Ca2+](i) was nearly completely attenuated. These data show that Ca2+ entry into PbTx-1-exposed CGNs occurs through three primary routes: NMDA receptor ion channels, L-type Ca2+ channels, and reversal of the Na+/Ca2+ exchanger. There was a close correlation between reduction of the integrated fluo-3 fluorescence response and the level of neuroprotection afforded by blockers of each Ca2+ entry pathway; however, simultaneous blockade of L-type Ca2+ channels and the Na+/Ca2+ exchanger, although reducing the integrated [Ca2+](i) response to a level below that provided by NMDA receptor blockade alone, failed to completely attenuate PbTx-1 neurotoxicity. This finding suggests that in addition to total [Ca2+](i) load, neuronal vulnerability is governed principally by the NMDA receptor Ca2+ influx pathway.

UR - http://www.scopus.com/inward/record.url?scp=0034066302&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0034066302&partnerID=8YFLogxK

U2 - 10.1046/j.1471-4159.2000.0741443.x

DO - 10.1046/j.1471-4159.2000.0741443.x

M3 - Article

VL - 74

SP - 1443

EP - 1451

JO - Journal of Neurochemistry

JF - Journal of Neurochemistry

SN - 0022-3042

IS - 4

ER -