Tetanus and botulinum toxins block the release of acetylcholine from slices of rat striatum and from the isolated electric organ of Torpedo at different concentrations.

Tetanus toxin, like botulinum toxin type A, blocks cholinergic synaptic transmission at the central and peripheral nervous systems. Nevertheless, the diseases induced by the two toxins are different since tetanus toxin induces a spastic paralysis and botulinum toxin elicits a flaccid paralysis. Thus, we have investigated the sensitivity of a central and a peripheral cholinergic synapse to these two toxins. We have studied the action of both poison on the release of acetylcholine from slices of the rat striatum and from the isolated electric organ of Torpedo, which is homologous to the neuromuscular junction. Acetylcholine release from the rat striatum was continuously monitored by a chemiluminescent method. The secretion of acetylcholine from the electric organ was estimated both by measuring the amplitude of the evoked electrical discharge from stacks of electroplaques, and by continuously monitoring the neurotransmitter release from isolated nerve terminals. Tetanus toxin blocks the electrical discharge of electric organ prisms, and also impairs the release of acetylcholine from the Torpedo electric organ nerve endings. Our results on acetylcholine release show that tetanus toxin is more potent than botulinum toxin type A at the central cholinergic synapse (tetanus/botulinum toxins potency ratio about 100-200) whereas botulinum toxin is the most potent at the peripheral cholinergic synapse (botulinum/tetanus toxins potency ratio about 100).