Effects of black widow spider venom and latrocrustatoxin on crustacean nerve cells: electrophysiological and ultrastructural study.

1. Black widow spider venom (BWSV), or crustacean-specific toxin purified from it (named latrocrustatoxin, LCT) were lethal for the crayfish. 2. Distortions in the EMG and motor activity pattern after LCT injection indicated venom effects on the crayfish nervous system. 3. In the isolated ventral nerve cord, transient activation of the "silent" interneurons and motoneurons occurred after BWSV or LCT application. 4. In the isolated nerve-muscle preparation, LCT application elicited an intense transmitter release resulting in the complete blockade of neuromuscular transmission. 5. Electron microscopic study of the nervous and muscle tissue in venom treated crayfish demonstrated certain destructive changes in the nervous cells especially in the nerve terminals. 6. The results suggest that the LCT acts as a presynaptic neurotoxin in the central and peripheral nervous system of the crayfish.