Immunoreactive avian pancreatic polypeptide occurs in nerves of the mammalian nasal mucosa and eustachian tube.

Nerves staining with antibodies against avian pancreatic polypeptide were detected in the mucosa of the nasal cavity and around the Eustachian tube of rats, guinea pigs, rabbits and cats. The nerves were numerous in guinea pig and rabbit but few in rat and cat. They were predominantly located around large and medium-sized blood vessels. Occasionally, single nerve fibres were noted around the acini of seromucous glands. This localization suggests that nerves storing immunoreactive avian pancreatic polypeptide are involved primarily in the regulation of local blood flow.