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 mollu sc Pecten maximus was investigated by immunocytochemistry. Positive FM RFamide-like immunoreactivity was detected in nerve fibres in close co ntact with exocrine alpha amylase secreting cells. Physiological studi es on enzymatically dissociated cells of the stomach-digestive gland c omplex 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 mo st naturally occurring vertebrate secretagogues which are hormones, FM RFamide appears to work in our in vitro system as a paracrine factor.