LOCALIZATION OF CORAZONIN IN THE NERVOUS-SYSTEM OF THE COCKROACH PERIPLANETA-AMERICANA

Antisera raised to the cardioactive peptide corazonin were used to loc alize immunoreactive cells in the nervous system of the American cockr oach. Sera obtained after the seventh booster injection were sufficien tly specific to be used for immunocytology. They recognized a subset o f 10 lateral neurosecretory cells in the protocerebrum that project to , and arborize and terminate in the ipsilateral corpus cardiacum. They also reacted with bilateral neurons in each of the thoracic and abdom inal neuromeres, a single dorsal unpaired median neuron in the suboeso phageal ganglion, an interneuron in each optic lobe, and other neurons at the base of the optic lobe, in the tritocerebrum and deutocerebrum . The presence of corazonin in the abdominal neurons and the lateral n eurosecretory cells was confirmed by HPLC fractionation of extracts of the abdominal ganglia, brains and retrocerebral complexes, followed b y determination of corazonin by ELISA, which revealed in each tissue a single immunoreactive peak co-eluting with corazonin in two different HPLC systems. Antisera obtained after the first three booster injecti ons recognized a large number of neuroendocrine cells and neurons in t he brain and the abdominal nerve cord. However, the sera from the two rabbits reacted largely with different cells, indicating that the majo rity of this immunoreactivity was due to cross-reactivity. These resul ts indicate that the production of highly specific antisera to some ne uropeptides may require a considerable number of booster injections.