Glutamatergic postsynaptic block by Pamphobeteus spider venoms in crayfish

Alfonso Araque, Wagner Ferreira, Silvia Lucas, Washington Buño

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9 Scopus citations


The effects of toxins from venom glands of two south american spiders (Pamphobeteus platyomma and P. soracabae) on glutamatergic excitatory synaptic transmission were studied in the neuromuscular junction of the opener muscle of crayfish. The toxins selectively and reversibly blocked both excitatory postsynaptic currents and potentials in a dose-dependent manner. They also reversibly abolished glutamate-induced postsynaptic membrane depolarization. They had no effect on resting postsynaptic membrane conductance nor on postsynaptic voltage-gated currents. The synaptic facilitation and the frequency of miniature postsynaptic potentials were unaffected by the toxins, indicating that presynaptic events were not modified. Picrotoxin, a selective antagonist of the γ-aminobutyric acid (GABA)A receptor, did not modify toxin effects. We conclude that both toxins specifically block the postsynaptic glutamate receptor-channel complex.

Original languageEnglish (US)
Pages (from-to)109-114
Number of pages6
JournalBrain Research
Issue number1
StatePublished - Jan 31 1992


  • Glutamate receptor
  • Neuromuscular junction
  • Neurotoxin
  • Postsynaptic block
  • Spider venom


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