Expression of interleukin-6 messenger RNA in a rat model of diffuse axonal injury

Having demonstrated a transcranial gradient of the cytokine interleukin-6 (IL-6) in patients with either traumatic brain injury or spontaneous subarachnoid haemorrhage we have employed in situ hybridisation for IL-6 messenger RNA (mRNA) to determine the site of this IL-6 production within the central nervous system (CNS). A rodent weight drop model of traumatic brain injury was used. IL-6 mRNA levels in brains were determined 6 h after injury. Sham animals had normal constitutive expression for IL6 mRNA. In traumatised animals an intense area of IL-6 mRNA labelling was found below the hippocampus. Cells strongly expressing IL-6 mRNA were also seen in the dentate gyrus. This inflammatory cytokine is clearly implicated in the response to CNS injury, but whether this response is neuroprotective or pathological is uncertain. (C) 2002 Elsevier Science Ireland Ltd. All rights reserved.