Background:Significantly increased plasma and CSF IL-6 levels reflect underlying tissue damage following clinical and experimental traumatic brain injury (TBI). Catecholamines, used under clinical conditions to maintain adequate cerebral perfusion pressure, induce a sustained IL-6 release. Thus an additional elevation in IL-6 could aggravate brain edema in the acute posttraumatic phase. We studied the changes in plasma and cerebrospinal fluid (CSF) IL-6 levels 4 and 24 hours after experimental TBI and assessed possible time-dependent effects of norepinephrine infusion on IL-6 and brain edema.Material/Methods:Paired plasma and CSF IL-6 measured at 4 and 24 hours following TBI (n=10) were compared to levels in non-traumatized rats (n=5). In a placebo-controlled trial, 20 brain-injured male Sprague-Dawley rats were randomized to receive norepinephrine or NaCl for 90 minutes at 4 or 24 hours after TBI. Plasma IL-6 was measured before, during, and after the infusion period. One hour after stopping the infusion, CSF IL-6 and hemispheric swelling were determined.Results:During the first posttraumatic day, plasma and CSF IL-6 levels were significantly increased compared to non-traumatized rats, reaching the highest values at 24 hours (p

Keywords: Brain Injuries - blood, Brain Injuries - cerebrospinal fluid, Edema, Interleukin-6 - blood, Interleukin-6 - metabolism, Norepinephrine - pharmacology, Sodium Chloride - pharmacology, Time Factors