A pharmacological and immunohistochemical study of the splanchnic innervation of ileal longitudinal muscle in the toad Bufo marinus

Abstract

A study was made of the innervation of the longitudinal muscle of the toad ileum with particular emphasis on the splanchnic innervation by non-adrenergic, noncholinergic (NANC) nerves. Nerve fibres containing substance P-like immunoreactivity (SP-LI) were observed in the gut wall and in the splanchnic nerves. Virtually no SP-LI fibres survived in the ileal wall after degenerative section of the splanchnic nerves. Incubation overnight in a high concentration of capsaicin (3×10-4 M) caused degeneration of SP-LI fibres. No evidence was obtained for enteric neurons containing SP-LI. Substance P caused a contraction of the longitudinal muscle similar to that produced by nerve stimulation. The res..