Interleukin-1 beta enhances spinal cord blood flow after intrathecal administration in the normal rat

Abstract

The effects of acute intrathecal recombinant human interleukin-1 beta (rhIL-1 beta) administration on spinal cord blood flow (SCBF), volume, and velocity were determined by laser-Doppler flowmetry in normal anesthetized rats with the use of a randomized and blinded protocol. The intrathecal administration of rhIL-1 beta (0.16-16 ng) produced a dose-dependent increase in SCBF that was not related to changes in blood pressure; arterial pH, PO2, PCO2; or spinal cord temperature. The IL-1 beta-induced enhancement of SCBF was directly proportional to the resultant elevation of spinal cord rhIL-1 beta content and was significantly correlated with an elevated blood velocity. The IL-1 receptor antagonist (IL-1ra) in concentrations 50- and 200-fold higher than IL-1 beta completely blocked the IL-1 beta-induced increase in SCBF when both compounds were administered concomitantly, but when administered alone, IL-1ra did not affect SCBF or other parameters. This suggests that IL-1 beta action was mediated by a specific interaction with an IL-1 membrane receptor site. The results suggest a role of IL-1 beta in the regulation of spinal cord hemodynamics. A potential pharmacological approach using IL-1 agonists for the treatment of the delayed appearance of posttraumatic spinal ischemia is proposed.