[Effects of biologically active peptides on the giant neurons of the giant African snail, Achatina fulica Férussac].

Effects of neuropeptides proposed as neurotransmitters of mammals and invertebrates and those of natural toxins, etc., on the identifiable giant neurones of an African giant snail (Achatina fulica Férussac) were examined. Oxytocin had a tendency to show the excitatory effects; this substance was excitatory on five neurones and inhibitory on one neurone. A substance related to oxytocin, vasotocin, also showed excitatory effects on the three neurones. On the other hand, FMR Famide was inhibitory on six neurones. Proctolin had excitatory effects on only one neurone.