Fulicin regulates the female reproductive organs of the snail, Achatina fulica.

Abstract Fulicin is a d -amino acid-containing neuropeptide that has been thought to control male copulatory behavior in the land snail, Achatina fulica . In the present study, we demonstrated that the vagina and the oviduct of Achatina were densely innervated by fulicin-like immunoreactive neuronal fibers. We confirmed that fulicin was actually present in the vagina by mass spectrometry. Furthermore, fulicin showed a profound excitatory effect on contractions of the vagina and the oviduct. These results suggest that fulicin controls female egg-laying behavior as an excitatory neuropeptide regulating the female reproductive organs of the snail.