Opposite Actions of the Anthozoan Neuropeptide Antho-Rnamide on Antagonistic Muscle Groups in Sea Anemones

Abstract

ABSTRACT Coelenterates are generally assumed to be primitive animals with simple nervous systems. We believe, however, that in at least one group, the sea anemones, the nervous system is in reality rather complex, a view supported by the growing number of neuropeptides recently extracted from these animals (Grim-melikhuijzen et al. 1990a,b). Three of these peptides (Antho-RFamide and the Antho-RWamides I and II) have demonstrable physiological actions on sea-anemone muscle preparations (McFarlane et al. 1987, 1990; McFarlane and Grimmelikhuijzen, 1991) and, in the case of the Antho-RWamides, on isolated muscle cells (McFarlane et al. 1991). Here we consider a fourth neuropeptide from sea anemones, Antho-RNamide (L-3-phenyllactyl-Leu-Arg-Asn-NH2) (Grim-melikhuijzen et al. 1990), and show that it has opposite actions on adjacent antagonistic muscles in sea anemones.