Effect of piperazine on central and peripheral cholinergic synapses of the frog.

The anthelmintic agent piperazine did not antagonize carbachol-induced depolarizations of the frog sartorius muscle but depressed root potentials and acetylcholine release from the frog spinal cord. We suggest that piperazine has a presynaptic site of action at central cholinergic nerve-terminals.