Nerve fibres containing gastrin-releasing peptide around pial vessels.
Nerve fibres containing immunoreactive gastrin-releasing peptide (GRP) were demonstrated around pial blood vessels of cat, guinea pig, rat, and mouse. A sparse supply was found around spinal cord blood vessels, whereas the choroid plexus seemed to be devoid of GRP fibres. Sympathectomy did not affect the number or distribution of the GRP fibres. The administration of neither GRP nor its closely related analogue, bombesin, contracted or dilated feline pial arteries in vitro.