ISOLATION, IDENTIFICATION, AND SYNTHESIS OF PDVDHFLRFAMIDE (SCHISTOFLRFAMIDE) IN LOCUSTA-MIGRATORIA AND ITS ASSOCIATION WITH THE MALE ACCESSORY-GLANDS, THE SALIVARY-GLANDS, THE HEART, AND THE OVIDUCT

An amidated decapeptide, exhibiting strong inhibitory activity of spon taneous visceral muscle movements, was isolated from 9000 brain-corpor a cardiaca-corpora allata-subesophageal ganglion complexes of the migr atory locust, Locusta migratoria. During the process of HPLC purificat ions, the biological activity of the fractions was monitored using the isolated hindgut of the cockroach Leucophaea maderae. The primary str ucture of this myotropic peptide is Pro-Asp-Val-Asp-His-Val-Phe-Leu-Ar g-Phe-NH2 and is identical to SchistoFLRFamide isolated from the grass hopper, Schistocerca gregaria. It shares the carboxy-terminal sequence FLRFamide with several identified peptides from different phyla. At t his moment, six decapeptides isolated from different insect species ar e identical at 7 of the 10 amino acid residues (X-D-V-X-H-X-FLRFamide) . The cockroach, fly, and locust peptides differ only by the N-termina l amino acid residue. Synthetic SchistoFLRFamide showed biological as well as chemical characteristics indistinguishable from the native pep tide. It provoked a decrease in frequency and amplitude of contraction s of the locust oviduct. By means of a polyclonal antiserum directed a gainst the carboxy terminal of SchistoFLRFamide, we demonstrated that the male accessory glands, the heart, the oviduct, and the salivary gl ands were innervated by axons containing SchistoFLRFamide-like immunor eactivity. Administration of SchistoFLRFamide elicited an immediate ef fect on the basal membrane potential of the opalescent tubule gland ce lls.