Regulatory peptides in parasitic platyhelminths.

Regulatory peptides are short chains of amino acids that regulate cell-to-cell interactions in widely divergent animal groups. Evidence is accumulating to suggest that they mediate many aspects of physiology and behaviour, serving as neurotransmitters, neuromodulators and hormones. While most data in this field derive from studies on the mammalian nervous and endocrine systems, the last decade has witnessed an upsurge of interest in invertebrate peptide biology, not least because it is likely that many regulatory peptides originated in the nervous system of invertebrates. Platyhelminths, like other invertebrate groups investigated, contain numerous neuropeptides, and here David Halton and colleagues review the evidence that these putative signalling agents serve key roles in parasite motility, reproduction and morphogenesis. The physicochemical differences between host and parasite peptides raise the possibility that selective disruption of peptidergic control systems in parasites could be an exploitable target in future chemotherapeutic strategies.