To compare the stomatogastric nervous system of the crayfish Cherax destructor 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 techniques and confocal microscopy. In addition, the number of cells in the stomatogastric
ganglion (19-24) and axon profiles in the stomatogastric nerve (157-165) were counted.
FLRFamide-like immunoreactivity was present within numerous cell bodies and neuropil of the commissural ganglia, in the neuropil of the stomatogastric
ganglion, and in one cell body of the esophageal
ganglion.
FLRFamide-like immunoreactivity was also found in two cell bodies at the junction of the stomatogastric nerve with the superior esophageal nerve and in two cell bodies in the inferior ventricular nerve.
Proctolin-like immunoreactivity was present in numerous cell bodies and neuropil of the paired commissural ganglia and in the neuropil of the stomatogastric
ganglion. CCAP-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 and on the postesophageal commissure, indicating a neurohemal source within the stomatogastric nervous system, which was verified by electron microscopy. The pericardial organs showed
FLRFamide-,
proctolin-, and CCAP-like immunoreactivity. This staining pattern suggests that
FLRFamide-like and
proctolin-like
peptides are used as
neurohormones and as
neuromodulators in the stomatogastric nervous system of the crayfish C. destructor, whereas CCAP-like
peptides may only affect the stomatogastric
ganglion as a
neurohormone.