Galanin-like immunoreactive nerve elements in the small intestine of the rat. An electron microscopic...

Nerve cell bodies and fibres showing galanin-like immunoreactivity have been demonstrated in rat small intestine using immunocytochemistry. Immunoreactive cell bodies were observed in both the myenteric and the submucous plexuses. Immunoreactive nerve fibres were observed in all layers of the small intestine, especially in both plexuses and in the inner circular muscle layer. The immunoreactive nerve processes were found in close association (sometimes separated by less than 40 nm) with smooth muscle cells. These terminals contained both agranular vesicles (30-40 nm) and large granular vesicles (80-120 nm). Immunoreactive nerve fibres were sometimes seen in perivascular plexuses. It is concluded that, in rat small intestine, neurones expressing galanin-like immunoreactivity project to several different sites and may participate in a number of mechanisms, including the regulation of smooth muscle activity, mucosal cell secretion and blood flow; galanin may also be involved in interneuronal activity.