Proctolin-like immunoreactivity in dorsal paired median neurons generating plateau action potentials in cockroach Periplaneta americana.

The proctolinergic nature of dorsal paired median (DPM) neurons generating plateau action potentials (PAPs) of the cockroach CNS has been demonstrated using a double labelling technique (lucifer yellow staining and proctolin-like immunochemistry). Electrophysiological results support morphological evidence that a direct pathway exists from axons passing throughout the proctodeal nerves to electrically active DPM neuron somata. However, the occurrence of spike failure along the neuritic membrane and the existence of a neuritic spike initiating site has been postulated because spontaneous PAPs recorded intracellularly were not associated on a one-to-one basis with peripheral axon spikes.