COMPARATIVE-ANALYSIS OF THE DISTRIBUTION OF BRADYKININ-LIKE, GYIRFAMIDE-LIKE AND NEUROPEPTIDE-F-LIKE IMMUNOREACTIVITIES IN THE MONOGENEAN, DICLIDOPHORA-MERLANGI

An indirect immunocytochemical technique combined with confocal scanni ng laser microscopy has been used to demonstrate immunoreactivities to the nonapeptide, RPPGFSPFR (bradykinin, BK) and the endogenous flatwo rm regulatory peptide, GYIRFamide in the nervous system of the monogen ean, Diclidophora merlangi. In addition, a simultaneous double-labelli ng technique was employed to examine possible co-localization of GYIRF amide- and neuropeptide F (NPF) immunoreactivities, using antisera to the C-terminal nonapeptide-amide of NPF (Moniezia expansa, FAIIGRPRF.N H2). BK immunostaining was restricted to a small population of nerve c ells and associated fibres within the Ventral nerve cords and to 2 pai rs of nerve cells innervating the cirrus and the pharynx, respectively . No immunopositive nerve cells and fibres were identified within the brain or in association with the female reproductive apparatus. In con trast, GYIRFamide staining was abundant throughout the central and per ipheral nervous systems, and appeared similar to the staining pattern revealed using an FMRFamide antiserum. GYIRFamide immunoreactivity was localized to nerve cells and fibres within the paired cerebral gangli a and the longitudinal ventral, dorsal and lateral nerve cords and the ir numerous interconnecting transverse commissures. The plexuses of th e buccal suckers, pharynx and clamps of the haptor were strongly immun opositive for GYIRFamide, as were nerve cells innervating the ootype, the oviduct and the vitelline reservoir of the reproductive apparatus. Double-labelling experiments indicated an apparent co-localization of GYIRFamide and NPF immunoreactivities.