RADIOIMMUNOASSAY DETERMINATION OF TACHYKININ-RELATED PEPTIDE IN DIFFERENT PORTIONS OF THE CENTRAL-NERVOUS-SYSTEM AND INTESTINE OF THE COCKROACH LEUCOPHAEA-MADERAE

A radioimmunoassay was developed for inset tachykinin-related peptides with the use of an antiserum raised to the locust neuropeptide locust atachykinin I (LomTK I). Determination of tachykinin-related peptide w as performed in different tissues of the cockroach Leucophaea maderae. The largest amounts of LomTK-like immunoreactivity (LomTK-LI) reside in the brain and in the midgut. Relatively large amounts were also fou nd in the suboesophageal ganglion and throughout the ganglia of the ve ntral nerve cord, whereas smaller amounts of LomTK-LI were detected in the corpora cardiaca, foregut and hindgut. Extracts of unfused abdomi nal ganglia and midguts, respectively, were analysed by a combination of reversed phase high performance liquid chromatography, and radioimm unoassay for LomTK-LI. The extracts of abdominal ganglia and midguts b oth contain LomTK-LI material which separates in at least two major co mponents. This LomTK-LI material had retention times corresponding app roximately to those of synthetic LomTK I and II. Since the cellular so urce of LomTK-LI material in the foregut and hindgut was not known fro m earlier studies, we investigated these tissues by immunocytochemistr y. We found that the LomTK-LI material associated with the foregut was in arborizing fibres in the oesophageal and gastric nerves and in the ingluvial ganglion. The amount of LomTK-LI material in other portions of the nervous system correlates well with previous immunocytochemica l data. We conclude that L. maderae have tow or more isoforms of tachy kinin-related peptides in the nervous system and intestine and that th ese are present in various amounts in different parts of the central n ervous system and intestine. The relative large amounts of LomTK-LI ma terial in the suboesophageal ganglion, oesophageal nerve and associate d ganglia and intestine indicate important roles of tachykinin-related peptides in feeding and digestion.