Substance P in the cerebral vasculature: depletion by capsaicin suggests a sensory role

Abstract

Measurements of substance P immunoreactivity confirms the presence of substance P-containing nerve fibers within the wall of cerebral blood vessels of guinea pigs, cats and rabbits. Low levels of somatostatin were also found in cerebral arteries of cats and rabbits. After treatment of guinea pigs with capsaicin, substance P levels in the cerebral circulation were markedly reduced, as was substance P in the mesenteric artery. Depletion of substance P by capsaicin suggests that cerebral arteries are innervated by primary afferent neurons, with a possible role in headache or reaction to trauma.