Simultaneous localization of a classical neurotransmitter (GABA) and a peptide transmitter candidate (proctolin) in the nervous system of the cockroach, Periplaneta americana.

The distribution of the neurotransmitter gamma-aminobutyric acid (GABA) in the 6th abdominal ganglion of the cockroach Periplaneta americana was investigated using an antiserum against GABA. The high number of GABA immunoreactive neurons refer to the important function of this transmitter substance. The relation between the GABAergic system and the proctolinergic system in the 6th abdominal ganglion was examined by means of an immunohistochemical double staining technique. The results show that probably GABA and proctolin do not coexist within one neuron.