REGIONAL LEVELS OF FREE FATTY-ACIDS AND EVANS BLUE EXTRAVASATION AFTER EXPERIMENTAL BRAIN INJURY

The recently developed controlled cortical-impact (CCI) model of brain injury in rats serves as an excellent tool to understand some of the neurochemical mechanisms mediating the pathophysiology of traumatic br ain injury. In this study, rats were subjected to lateral CCI brain in jury of low-grade severity. Their brains were frozen in situ at variou s times after injury to measure regional levels of free fatty acids. T issue total free fatty acids at the injury site within the left cortex were increased at 30 min, 2.5 h, and 24 h postinjury. In injured anim als, increases in stearic and arachidonic acids were slightly greater than those in palmitic and oleic acids. The levels of total free fatty acids in the cortex adjacent to the injury site were also increased i n injured animals at 2.5 h and 24 h after injury (p < 0.05). Only stea ric and arachidonic acids were observed to be significantly increased (p < 0.05) in the adjacent cortex of injured animals at all times afte r injury. Although no significant increases in total free fatty acids were observed in the left hippocampus adjacent to the injury site, ste arate and arachidonate concentrations were increased at 30 min and 2.5 h after injury (p < 0.05). Extravasation of Evans blue was found to b e significantly increased in the ipsilateral cortex of injured animals at 30 min and 10 h after brain injury. These results indicate the deg radation of membrane phospholipids and blood-brain barrier breakdown i n the ipsilateral cortex after lateral CCI brain injury. These results also suggest that arachidonic acid and its metabolites may play a rol e as a mediator in the blood-brain barrier breakdown associated with c ortical impact brain injury in rats.