A simple technique for monitoring the synaptic actions of pharmacological agents

A simple electrophysiologocal method for the pharmacological investigation of synaptic transmission in insects is described. By means of this technique synaptic potentials and ganglionic polarization can be recorded from the sixth abdominal ganglion of Periplaneta americana L. for long periods. In the absence of stimulation, spontaneous excitatory (EPSP) and inhibitory (IPSP) postsynaptic potentials can be recorded. The mechanical stimulation of cercal receptors demonstrates the summation of EPSPs leading to spike generation. Electrical stimulation of the cercal nerves (X, XI) enables the recording of a monosynaptic EPSP (XI) and a bisynaptic IPSP (X). The action of acetylcholine on synaptic transmission, including a dose response curve, is described. The potential of this technique as a tool in pharmacological research is discussed.