LOCALIZATION OF DIPLOPTERA-PUNCTATA ALLATOSTATIN-LIKE IMMUNOREACTIVITY IN HELMINTHS - AN IMMUNOCYTOCHEMICAL STUDY

The nervous systems of helminths are predominantly peptidergic in natu re, although it is likely that the full range of regulatory peptides u sed by these organisms has yet to be elucidated. Attempts to identify novel helminth neuropeptides are being made using immunocytochemistry with antisera raised against peptides isolated originally from insects . One of these antisera was raised against allatostatin III, a peptide isolated originally from the cockroach, Diploptera punctata, and a me mber of a family of related peptides found in insects. Allatostatin im munoreactivity was found throughout the nervous systems of Mesocestoid es corti tetrathyridia, and adult Moniezia expansa, Diclidophora merla ngi, Fasciola hepatica, Schistosoma mansoni, Ascaris suum and Panagrel lus redivivus. Immunostaining was observed in the nerve cords and ante rior ganglia of all the helminths. It was also apparent in the subtegu mental nerves and around the reproductive apparatus of the flatworms, in neurones in the pharynx of D. merlangi, F. hepatica, A. suum and P. redivivus, and in fibres innervating the anterior sense organs in the nematodes. Immunostaining in all species was both reproducible and sp ecific in that it could be abolished by pre-absorption of the antiseru m with allatostatins I-IV. These results suggest that molecules relate d to the D. punctata allatostatins are important components in the ner vous systems of a number of helminth parasites, and a free-living nema tode. Their distribution within the nervous system suggests they funct ion as neurotransmitters/ neuromodulators with roles in locomotion, fe eding, reproduction and sensory perception.