Internal chemical communication within flatworms

Immunocytochemical localization of regulatory peptides in six species of trematode parasites

1. Frozen and paraffin sections of six species of trematodes: Schistosoma mansoni, S. mattheei, S. japonicum, Schistosomatium douthitti, Echinostoma paraensei and Fasciola hepatica have been incubated with antisera against leu-enkephalin, FMRF-amide, gastrin-17, luteinizing hormone releasing hormone, neurotensin, oxytocin, prolactin, substance P, thyroid stimulating hormone and cholecystokinin, using indirect immunofluorescence and biotin-avidin horseradish peroxidase detection systems. 2. Of the ten antisera tested, six (leu-enkephalin, FMRF-amide, gastrin-17, luteinizing hormone releasing hormone, substance P and cholecystokinin) showed significant immunoreactivity, primarily in the central and peripheral nervous system, and also perhaps in the osmoregulatory system of the three species of Schistosoma. 3. Immunopositive nerve fibers extended from ganglia to gut wall, uterus and vitelline follicles, and especially from subtegumental nerve plexi to sensory receptors on the surface or in dorsal nippled tubercles.

Immunocytochemical demonstration of neuropeptides and serotonin in the nervous systems of adult Schistosoma mansoni

In the nervous system of adult Schistosoma mansoni, neuropeptides and serotonin were demonstrated immunocytochemically. Neurons and nerve fibers immunoreactive to anti-FMRF-amide, anti-substance P, anti-leu-enkephalin, and anti-growth hormone releasing factor were found in the central and peripheral nervous system. The peptidergic nerve cell bodies in the bilobed brain are large and often multipolar; those in the peripheral nerve net are smaller and often bipolar. Sensory receptors of two morphologically different types were found along the surface of the worm. They are mainly immunoreactive to anti-substance P and anti-leu-enkephalin, and, to a lesser degree, to anti-FMRF-amide. Serotonin-immunoreactive fibers are found in the central and peripheral nervous elements as well as in sensory endings.