Phoneutria spider toxins block ischemia-induced glutamate release, neuronal death, and loss of neurotransmission in hippocampus.
The aim of this study was to investigate the effect of spider toxins on brain injury induced by oxygen deprivation and low glucose (ODLG) insult on slices of rat hippocampus. After ODLG insult cell viabilility in hippocampal slices was assessed by confocal microscopy and epifluorescence using the live/dead kit containing calcein-AM and ethidium homodimer and CA1 population spike amplitude recording during stimulation of Schaffer collateral fibers. Spider toxins Tx3-3 or Tx3-4 and conus toxins, omega-conotoxin GVIA or omega-conotoxin MVIIC are calcium channel blockers and protected against neuronal damage in slices subjected to ODLG insult. Confocal imaging of CA1 region of rat hippocampal slices subject to ischemic insult treated with Tx3-3, Tx3-4, omega-conotoxin GVIA or omega-conotoxin MVIIC showed a decrease in cell death that amounted to 68 +/- 4.2%, 77 +/- 3.8%, 32 +/- 2.3%, and 46 +/- 2.9%, respectively. This neuroprotective effect of Tx3-4 was corroborated by eletrophysiological recordings of population spikes amplitudes in CA1. The neuroprotection promoted on hippocampal slices by Tx3-3 or Tx3-4 was also observed when the toxins were applied 10, 20, 30, 60, 90, or 120 min after induction of the ODLG injury. During the ischemic insult, glutamate release from slices was increased by 71% (from 7.0 +/- 0.3 nM/mg of protein control slices not subjected to ischemia to 12 +/- 0.4 nM/mg of protein in slices exposed to ischemia). Tx3-3, Tx3-4, omega-conotoxin GVIA or omega-conotoxin MVIIC inhibited the ischemia-induced increase on glutamate release by 54, 72, 60, and 70%, respectively. Thus Tx3-3 and Tx3-4 provided robust ischemic neuroprotection showing potential as a novel class of agent that exerts neuroprotection in an in vitro model of brain ischemia.
Laboratorio Neurociencia, Faculdade Medicina UFMG, Belo Horizonte, MG, Brazil.
Ana Cristina do Nascimento
AC
Pinheiro
Adriano Jesus
AJ
da Silva
Marco Antonio M
MA
Prado
Marta do Nascimento
Mdo N
Cordeiro
Michael
M
Richardson
Monalise Costa
MC
Batista
Célio José
CJ
de Castro Junior
André Ricardo
AR
Massensini
Cristina
C
Guatimosim
Marco A
MA
Romano-Silva
Christopher
C
Kushmerick
Marcus Vinicius
MV
Gomez
D000704:Analysis of Variance; D000818:Animals; D002121:Calcium Channel Blockers / Q000494:pharmacology; D016923:Cell Death / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D018698:Glutamic Acid / Q000378:metabolism*; D006624:Hippocampus / Q000187:drug effects / Q000473:pathology*; D066298:In Vitro Techniques; D007511:Ischemia / Q000188:drug therapy / Q000473:pathology*; D009474:Neurons / Q000187:drug effects*; D009479:Neuropeptides / Q000494:pharmacology; D018408:Patch-Clamp Techniques / Q000379:methods; D051381:Rats; D017208:Rats, Wistar; D013111:Spider Venoms / Q000494:pharmacology*; D009435:Synaptic Transmission / Q000187:drug effects*; D013997:Time Factors; D020866:omega-Conotoxin GVIA / Q000494:pharmacology; D020960:omega-Conotoxins / Q000494:pharmacology
D002121:Calcium Channel Blockers; D009479:Neuropeptides; D013111:Spider Venoms; C098736:Tx3 neurotoxin; D020960:omega-Conotoxins; C075851:omega-conotoxin-MVIIC; D018698:Glutamic Acid; D020866:omega-Conotoxin GVIA