Immunocytochemical localization of FLRFamide-, proctolin-, and CCAP-like peptides in the stomatogastric nervous system and neurohemal structures of the crayfish, Cherax destructor

To compare the stomatogastric nervous system of the crayfish Cherax destruc tor with those of other decapod species, the distribution of FLRF (Phe-Leu- Arg-Phe) amide-, proctolin- and crustacean cardioactive peptide (CCAP)-like immunoreactivities was studied in the stomatogastric nervous system and in neurosecretory structures by using wholemount immunocytochemical technique s and confocal microscopy. In addition, the number of cells in the stomatog astric ganglion (19-24) and axon profiles in the stomatogastric nerve (157- 165) were counted. FLRFamide-like immunoreactivity was present within numer ous cell bodies and neuropil of the commissural ganglia, in the neuropil of the stomatogastric ganglion, and in one cell body of the esophageal gangli on. FLRFamide-like immunoreactivity was also found in two cell bodies at th e junction of the stomatogastric nerve with the superior esophageal nerve a nd in two cell bodies in the inferior ventricular nerve. Proctolin-like imm unoreactivity was present in numerous cell bodies and neuropil of the paire d commissural ganglia and in the neuropil of the stomatogastric ganglion. C CAP-like immunoreactivity was found in the neuropil and in one to four cell bodies in the commissural ganglia. Both proctolin- and CCAP-immunoreactive varicosities occurred on the surface of the circumesophageal connectives a nd on the postesophageal commissure, indicating a neurohemal source within the stomatogastric nervous system, which was verified by electron microscop y. The pericardial organs showed FLRFamide-, proctolin-, and CCAP-like immu noreactivity. This staining pattern suggests that FLRFamide-like and procto lin-like peptides are used as neurohormones and as neuromodulators in the s tomatogastric nervous system of the crayfish C. destructor, whereas CCAP-li ke peptides may only affect the stomatogastric ganglion as a neurohormone. (C) 1999 Wiley-Liss, Inc.