Cholinergic, serotoninergic and peptidergic components of the nervous system of Discocotyle sagittata (Monogenea: Polyopisthocotylea)

Cholinergic, serotoninergic (5-HT) and peptidergic neuronal pathways have been demonstrated in both central and peripheral nervous systems of adult Discocotyle sagittata, using enzyme histochemistry and indirect immunocytochemistry in conjunction with confocal scanning laser microscopy. Antisera to 2 native flatworm neuropeptides, neuropeptide F and the fMRFamide-related peptide (FaRP), GNFFRFamide, were employed to detect peptide immunoreactivity. The CNS is composed of paired cerebral ganglia and connecting dorsal commissure, together with several paired longitudinal nerve cords. The main longitudinal nerve cords (lateral, ventral and dorsal) are interconnected at intervals by a series of annular cross-connectives, producing a ladder-like arrangement typical of the platyhelminth nervous system. At the lever of the haptor, the ventral cords provide nerve roots which innervate each of the 8 clamps. Cholinergic and peptidergic neuronal organisation was similar, but distinct from that of the serotoninergic components. The PNS and reproductive system are predominantly innervated by peptidergic neurones. Copyright (C) 1996 Australian Society for Parasitology. Published by Elsevier Science Ltd.

Immunohistochemical localization of a Shaker-related voltage-gated potassium channel protein in Schistosoma mansoni (Trematoda: Digenea)

We have recently isolated a cDNA (SKV1.1) encoding a Shakei-related K+ channel from the human parasitic trematode Schistosoma mansoni. In order to better understand the functions of SKv1.1 protein, the distribution of SKv1.1 protein in adult S. mansoni was analyzed by immunohistochemistry using a region-specific antibody. SKV1.1 proteins were widely expressed in the nervous and muscular systems. The strongest immunoreactivity (IR) was observed in the nervous system of both male and female. In the nervous system, IR for SKv1.1 proteins was localized in cell bodies and nerve fibers of the anterior ganglia, the central commissure, and the main nerve cords. IR was also observed in the dorsal and the ventral peripheral nerve nets, fine nerve fibers entering into a variety of structures such as the dorsal tubercles, longitudinal and ventral muscle fibers, and oral and ventral suckers. In the muscular system, SKv1.1 proteins were localized to the longitudinal, circular, and ventral muscle fibers of male as well as in isolated muscle fibers where native A-type K+ currents were measured. Moderate IR was also seen in a large number of cell bodies in the parenchyma. These results indicate that SKv1.1 protein may play an important role in the regulation of the excitability of neurons and muscle cells of S. mansoni. (C) 1995 Academic Press, Inc.

5-HYDROXYTRYPTAMINE-IMMUNOREACTIVITY IN THE MONOGENEAN PARASITE, ENTOBDELLA-SOLEAE

5-HT-immunoreactivity in Entobdella soleae was found to be extensive throughout both the central and peripheral nervous systems, with the strongest staining occurring in the innervation of the forebody, most notably in the paired cerebral ganglia, pharynx and adhesive pads. In the reproductive system, staining was evident throughout the numerous cell bodies and fibres innervating the musculature of the egg-assembly apparatus. The haptor contained an extensive array of serotoninergic fibres derived from the main longitudinal cords; this array was associated with the haptoral muscles and sclerites, and possibly with the ventral sensory papillae.