The effect of a single intraperitoneal dose of hrIL-1α on substance P-, neurokinin A-, calcitonin gene-related peptide- and neuropeptide Y-like immunoreactivity in cerebrospinal fluid, plasma and knee joint synovial fluid in the rat

Abstract

Substance P (SP)-, neurokinin A (NKA)-, calcitonin gene-related peptide (CGRP)- and neuropeptide Y (NPY)-like immunoreactivity (-LI) was studied in rats' cerebrospinal fluid (CSF), plasma and synovial fluid (SF) from both knee joints at 2 and 24 h following an intraperitoneal administration of 0.05 ml human recombinant interleukin-1α (i.p. hrIL-1α) or saline. Increased or decreased levels of SP-, NKA and CGRP-LI were detected in CSF and plasma, whereas NPY-LI was unaffected. In SF only CGRP-LI increased bilaterally. There was a correlation in CGRP-LI content between plasma and CSF following i.p. hrIL-1α but not between plasma and SF or CSF and SF. It can be concluded that (1) i.p. hrIL-1α activates somatosensory afferents thereby increasing SP- and CGRP-LI content in CSF and plasma and NKA-LI in CSF; 2) i.p. hrIL-1α induces a bilateral increase of CGRP-LI in SF which is not mediated through systemic circulation and is possibly a part of the general host defensive reaction.