ANNETOCIN, AN ANNELID OXYTOCIN-RELATED PEPTIDE, INDUCES EGG-LAYING BEHAVIOR IN THE EARTHWORM, EISENIA-FOETIDA

Annetocin, an oxytocin-related peptide which we isolated from the eart hworm Eisenia foetida, induced a series of egg-laying-related behavior s in the earthworms. These stereotyped behaviors consisted of well-def ined rotatory movements, characteristic body-shape changes, and mucous secretion from the clitellum. Each of these behaviors is known to be associated with formation of the cocoon in which eggs are deposited. I n fact, some of the earthworms injected with annetocin (>5 nmol) laid eggs. Such egg-laying-related behaviors except for oviposition were al so induced by oxytocin, but not by Arg-vasopressin and some other bioa ctive peptides isolated from E. foetida. Furthermore, annetocin also i nduced these egg-laying-like behaviors in the leech Whitmania pigra, b ut not in the polychaete Perinereis vancaurica. These results suggest that annetocin plays some key role in triggering stereotyped egg-layin g behaviors in terrestrial or freshwater annelids that have the clitel la. (C) 1996 Wiley-Liss, Inc.