A NEW BIOLOGICAL-ACTIVITY FOR THE NEUROPEPTIDE FMRFAMIDE - EXPERIMENTAL-EVIDENCE FOR A SECRETAGOGUE EFFECT ON AMYLASE SECRETION IN THE SCALLOP PECTEN-MAXIMUS

FMRFamide immunoreactivity in the digestive tract of the bivalve mollusc Pecten maximus was investigated by immunocytochemistry. Positive FMRFamide-like immunoreactivity was detected in nerve fibres in close contact with exocrine alpha amylase secreting cells. Physiological studies on enzymatically dissociated cells of the stomach-digestive gland complex demonstrated the involvement of FMRFamide and analogues in the control of alpha amylase release from the cells. The FMRFamide-induced secretion was shown to be time- and dose-dependent. In contrast to most naturally occurring vertebrate secretagogues which are hormones, FMRFamide appears to work in our in vitro system as a paracrine factor.