Immunocytochemical Localization of Leucomyosuppressin (LEM-MS) in the CNS of the Cockroach, Leucophaea Maderae and the Stable Fly, Stomoxys Calcitrans

Abstract

Major strides have been made in the past five years in the discovery of new insect neuropeptides due to the development of improved technology and instrumentation. A group of 12 neuropeptides were isolated and identified from extracts of Leucophaea maderae by G. M. Holman and collaborators between 1986 and 1987 (Holman et al., 1988). These neuropeptides consisted of 11 myotropic peptides and one myoinhibitory peptide. Holman et al.(1986) named the latter peptide Leucomyosuppressin (LEM-MS) and determined it to be a decapeptide with the structure, pGlu-Asp-Val-Asp-His-Val-Phe-Leu-Arg-Phe-NH₂. This neuropeptide structurally resembles the molluscan tetrapeptide, FMRFamide (Phe-Met-Arg-Phe-NH₂) which, interestingly, is a cardioaccelerator in molluscs, while LEM-MS inhibits contraction of both visceral and skeletal muscle of insects (Yamamoto et al., 1988). As a prelude to physiological investigations of this peptide, a study was done to locate the cells of origin and the neural pathway of LEM-MS in L. maderae using immunological probes. In order to determine if similar peptides are present in other orders of insects, antibodies to LEM-MS were also tested on tissues of the stable fly, Stomoxys calcitrans. These antibodies were visualized in adult specimens with fluorescent and peroxidase probes.