Peptide-containing neurones connect the two ganglionated plexuses of the enteric nervous system.

The enteric nervous system (ENS) of the mammalian gut consists principally of two ganglionated plexuses, the myenteric and submucous, which are embedded in the gut wall. Little is known about the anatomical and functional connections between the two plexuses and further clarification of their relationship is of central importance for the understanding of the ENS. In the present study we have approached this problem in a new way, using methods we have previously developed for maintaining the myenteric and submucous plexuses separately in vitro for several weeks. In an immunohistochemical study of these preparations and also of sections from normal and extrinsically denervated gut wall, we have found evidence for reciprocal projections between the myenteric and submucous plexuses, by nerve fibres containing two putative neurotransmitters, vasoactive intestinal polypeptide (VIP) and substance P (ref. 5) (see Fig. 1). Our observations were supported by radioimmunoassay of tissue extracts. These results suggest that one of the roles of these peptides in the gut is to coordinate the function of the two enteric plexuses.