PhTx3-4, a Spider Toxin Calcium Channel Blocker, Reduces NMDA-Induced Injury of the Retina.

The in vivo neuroprotective effect of PhTx3-4, a spider toxin N-P/Q calcium channel blocker, was studied in a rat model of NMDA-induced injury of the retina. NMDA (N-Methyl-D-Aspartate)-induced retinal injury in rats reduced the b-wave amplitude by 62% ± 3.6%, indicating the severity of the insult.

Phoneutria spider toxins block ischemia-induced glutamate release and neuronal death of cell layers of the retina.

Purpose: To investigate the effect of calcium channel blockers, spider toxins, on cell viability and the glutamate content of ischemic retinal slices.

Methods: Rat retinal slices were subjected to ischemia via exposure to oxygen-deprived low-glucose medium for 45 minutes. Slices were either treated or not treated with the toxins PhTx3, Tx3-3, and Tx3-4.

The effect of spider toxin PhTx3-4, ω-conotoxins MVIIA and MVIIC on glutamate uptake and on capsaicin-induced glutamate release and [Ca2+]i in spinal cord synaptosomes.

In spinal cord synaptosomes, the spider toxin PhTx3-4 inhibited capsaicin-stimulated release of glutamate in both calcium-dependent and -independent manners. In contrast, the conus toxins, ω-conotoxin MVIIA and xconotoxin MVIIC, only inhibited calcium-dependent glutamate release. PhTx3-4, but not ω-conotoxin MVIIA or xconotoxin MVIIC, is able to inhibit the uptake of glutamate by synaptosomes, and this inhibition in turn leads to a decrease in the Ca(2+)-independent release of glutamate.

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.