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T.A. Day and A.G. Maule
Peptides 20:999-1019
Parasitic worms come from two very different phyla, Platyhelminthes
(flatworms) and Nematoda (roundworms). Although both phyla possess
nervous systems with highly developed peptidergic components,
there are key differences in the structure and action of native
neuropeptides in the two groups. For example, the most abundant
neuropeptide known in platyhelminths is the pancreatic polypeptide-like
neuropeptide F, while the most prevalent neuropeptides in nematodes
are FMRFamide-related peptides (FaRPs) which are also present
in platyhelminths. With respect to neuropeptide diversity, platyhelminth
species possess only one or two distinct FaRPs, whereas nematodes
have upwards of 50 unique FaRPs. FaRP bioactivity in platyhelminths
appears to be restricted to myoexcitation whereas both excitatory
and inhibitory effects have been reported in nematodes. Interest
has recently focused on the peptidergic signalling systems of
both phyla because elucidation of these systems will do much to
clarify the basic biology of the worms, and because the peptidergic
systems hold the promise of yielding novel targets for a new generation
of antiparasitic drugs.