Black widow spider venom: excitatory action on hippocampal neurons.

Electrical activities of thin hippocampal sections of the guinea pig were studied in vitro during and after administration of black widow spider venom (BSV). In CA3 neurons, BSV induced spontaneous discharges which were suppressed by Co2+ or Mn2+. During BSV administration, trains of potential changes resembling excitatory postsynaptic potentials (EPSPs) were recorded intracellularly. The EPSP-like potentials were blocked by TTX. BSV seems to induce impulses in presynaptic fibers or terminals and thereby facilitates release of neurotransmitters.