A CYTOCHEMICAL STUDY OF THE NERVOUS-SYSTEM OF THE PROTEOCEPHALIDEAN CESTODE, PROTEOCEPHALUS-POLLANICOLA

The localization and distribution of cholinergic, serotoninergic and p eptidergic nerve elements in the proteocephalidean tapeworm, Proteocep halus pollanicola, have been investigated by enzyme histochemistry, an d by an indirect immunofluorescence technique interfaced with confocal scanning laser microscopy. Cholinesterase (ChE) activity was localize d in the major components of the central nervous system (CNS) and the peripheral nervous system (PNS), including the innervation of the repr oductive structures of the worm. Serotoninergic (5-HT) nerves were fou nd in the paired cerebral ganglia, transverse commissure and in the 10 longitudinal nerve cords. Antisera to 17 mammalian regulatory peptide s and the invertebrate peptide FMRFamide have been used to explore the peptidergic nervous system of the worm. The most extensive immunostai ning occurred with antisera raised to members of the neuropeptide Y su perfamily, namely neuropeptide Y (NPY), peptide YY (PYY) and pancreati c polypeptide (PP). In all cases, intense immunoreactivity was found i n numerous cell bodies and fibres of both the CNS and PNS, including t he innervation of the reproductive apparatus. FMRFamide antisera stain ed the same structures to a comparable degree as those raised to the N PY superfamily. Cholinergic and peptidergic elements were much more pr evalent within the CNS, while the serotoninergic nerve fibres tended t o dominate in the PNS. The overlap obtained in staining patterns for t he peptidergic and cholinergic components suggests that there may be a certain amount of co-localization of peptides with small-molecule tra nsmitter substances in the same neurone. Weak staining for the tachyki nin, substance P and for calcitonin gene-related peptide(CGRP) was con fined to the major longitudinal nerve cords.