Temporal profile of cerebrospinal fluid glutamate, interleukin-6, and tumor necrosis factor-alpha in relation to brain edema and contusion following controlled cortical impact injury in rats

Abstract

Traumatic brain injury is associated with release of the excitotoxin glutamate and production of pro-inflammatory cytokines IL-6 and tumor necrosis factor-alpha (TNF-alpha). Following controlled cortical impact injury, cerebrospinal fluid (CSF) glutamate, IL-6, and TNF-alpha concentrations were measured to investigate their relationship to evolving tissue damage. Compared to non-traumatized rats CSF glutamate, IL-6 and TNF-alpha levels were significantly increased by 8 h after trauma (P<0.005). Parallel to increasing brain swelling and contusion CSF glutamate was significantly elevated over time, reaching highest levels by 48 h (33+/-4 microM) while IL-6 and TNF-alpha showed maximum values at 24 h after trauma (42+/-7 and 4.7+/-1 pg/ml) (P<0.005). The observed different temporal profile of CSF glutamate, IL-6, and TNF-alpha following focal traumatic brain injury could be of therapeutic importance.