Platyhelminth FMRFamide-related peptides (FaRPs) contract Schistosoma mansoni (Trematoda: Digenea) muscle fibres in vitro.
Molluscan FMRFamide and two recently discovered platyhelminth FMRFamide-related peptides (FaRPs), GNFFRFamide from the cestode Moniezia expansa and RYIRFamide from the terrestrial turbellarian Artioposthia triangulata, cause dose-dependent contractions of individual muscle fibres from Schistosoma mansoni in vitro. The most potent FaRP tested was the turbellarian peptide RYIRFamide, which produced a concentration-dependent effect between 10(-9) and 10(-7) M. FMRFamide and GNFFRFamide were less potent, inducing contractions between 10(-8)-10(-6) M and 10(-7)-10(-5) M respectively. The contractile effect of each of these peptides was blocked by the presence of 1 microM FMR-D-Famide. FMRF free acid did not elicit contraction of the muscle fibres. The FaRP-induced contractions did not occur if the Ca2+ was omitted and 0.5 microM EGTA was added to the extracellular medium. The FaRP-induced contractions were not blocked by the Ca2+ channel blockers nicardipine, verapamil or diltiazem, although high K+-induced contractions of these fibres were blocked by nicardipine. These data indicate the presence of FaRP receptors on schistosome muscle fibres and demonstrate their ability to mediate muscle contraction. The action of these endogenous flatworm peptides on schistosome muscle is the first demonstration of a direct excitatory effect of any putative neurotransmitter on the muscle of a flatworm, and establishes a role for FaRPs in neuromuscular transmission in trematodes. In addition, it provides the first evidence that the peptidergic nervous system is a rational target for chemotherapeutic attack in parasitic platyhelmiths.
Day
T A
TA
Department of Zoology, Michigan State University, East Lansing 48824.
Maule
A G
AG
Shaw
C
C
Halton
D W
DW
Moore
S
S
Bennett
J L
JL
Pax
R A
RA
D000595:Amino Acid Sequence; D000818:Animals; D002118:Calcium / Q000494:pharmacology; D002121:Calcium Channel Blockers / Q000494:pharmacology; D004533:Egtazic Acid / Q000494:pharmacology; D019835:FMRFamide; D015801:Helminth Proteins / Q000737:chemistry / Q000494:pharmacology; D066298:In Vitro Techniques; D008969:Molecular Sequence Data; D009119:Muscle Contraction / Q000187:drug effects; D009479:Neuropeptides / Q000737:chemistry / Q000494:pharmacology*; D009842:Oligopeptides / Q000737:chemistry / Q000494:pharmacology; D010986:Platyhelminths; D018010:Receptors, Invertebrate Peptide / Q000187:drug effects / Q000378:metabolism; D012550:Schistosoma mansoni / Q000187:drug effects* / Q000502:physiology
D002121:Calcium Channel Blockers; C055209:FMRFamide receptor; D015801:Helminth Proteins; D009479:Neuropeptides; D009842:Oligopeptides; D018010:Receptors, Invertebrate Peptide; C086754:arginyl-tyrosyl-isoleucyl-arginyl-phenylalaninamide; C082029:GNFFRF-amide protein, Moniezia expansa; D004533:Egtazic Acid; D019835:FMRFamide; D002118:Calcium