IMMUNOHISTOCHEMICAL LOCALIZATION OF PACAP IN THE OVINE DIGESTIVE-SYSTEM

The localization of immunoreactive PACAP (PACAP-IR) in the entire leng th of the sheep gastrointestinal tract and the pancreas was studied by an immunohistochemical method. PACAP-IR-containing nerve fibers inner vated the longitudinal smooth muscle layer of the mucosa in the esopha gus, stomach, and small and large intestines, the muscular layer of th e stomach and intestine, Brunner's gland of the duodenum, and the wall s of small arteries. PACAP-IR fibers also innervated the exocrine acin i, islets of Langerhans, and the small arteries in the connective tiss ue septa of the pancreas. These findings suggest a regulatory role of PACAP in the digestive system.