Allatostatin-like immunoreactivity in the stomatogastric nervous system and the pericardial organs of the crab Cancer pagurus, the lobster Homarus americanus, and the crayfish Cherax destructor and Procambarus clarkii

The distribution of allatostatin (AST)-like immunoreactivity was studied in the stomatogastric nervous system (STNS) and the neurosecretory pericardia l organs (PO) of four decapod crustacean species by using wholemount immuno cytochemical techniques and confocal microscopy. AST-like immunoreactivity was found within the STNS of all four species; its distribution in each was unique. In all four species, AST-like immunoreactivity was present in the paired commissural ganglia (CoG), in the esophageal ganglion (OG), in the s tomatogastric ganglion (STG), and in their connecting nerves. Within the Co Gs, numerous cell bodies and neuropil were stained. In the OG, two cell bod ies were immunoreactive, although their branching pattern varies between sp ecies. In the STG of C. pagurus and H. americanus, neuropil was stained ext ensively, but no labeled cell bodies were found. Surprisingly, in C. destru ctor and P. clarkii, cell bodies were stained in the STG, one brightly stai ned cell body in both species and an additional two to five weakly stained cell bodies in P. clarkii. In all four species, stained gastropyloric recep tor cells were present. In contrast to the variable staining within the STN S, all four species have a similar pattern of AST-like immunoreactivity wit hin the PO. Only in C. destructor, AST-immunoreactive varicosities occur on the surface of the circumesophageal connectives and on the postesophageal commissure and suggest another neurohaemal source for AST-Like peptides in this species. The pattern of this staining suggests that AST-like peptides are likely utilized as both neurohormones and as neuromodulators in the STN S of decapod crustacea. J. Comp. Neurol. 403:85-105, 1999. (C) 1999 Wiley-L iss, Inc.