Effects of histamine on neuropeptide release into the knee joint perfusate and cerebrospinal fluid in rats.

In the present study we examined the effect of histamine injection on neuropeptide release in vivo in rats. Rats were injected with histamine either into the left knee joint or intraperitoneally. Concentrations of substance P (SP)-, neurokinin A (NKA)-, calcitonin gene-related peptide (CGRP)- and neuropeptide Y (NPY)-like immunoreactivity (-LI) were examined in the knee joint perfusates and cerebrospinal fluid at 2, 6 and 24 h following injection, by radioimmunoassay. Results show that intraarticular injection of histamine induced a bilateral release of SP-, NKA- and CGRP-LI in the knee joint perfusates while intraperitoneal injection of histamine induced a release of SP-, NKA- and CGRP-LI into the cerebrospinal fluid. No changes in concentrations of NPY-LI were observed following histamine injection. Results of the present study indicate that histamine selectively stimulates sensory neurons without affecting sympathetic. The increased concentrations of sensory neuropeptide-LI in the cerebrospinal fluid following intraperitoneal administration of histamine indicate a new mechanism by which histamine may exert systemic effects during inflammation and allergy.