EFFECT OF DIFLUOROMETHYLORNITHINE TREATMENT ON REGIONAL ORNITHINE DECARBOXYLASE ACTIVITY AND EDEMA FORMATION AFTER EXPERIMENTAL BRAIN INJURY

This study examined the effect of difluoromethylornithine (DFMO) on re gional activities of ornithine decarboxylase (ODC) and edema formation in bilateral cerebral cortex and hippocampus after a unilateral contr olled cortical-impact (CCI) injury in rats. To measure the activity of ODC, the brains of injured and control rats were frozen in situ at 30 min, 3, 6, and 24 h after CCI brain injury of moderate severity. The specific gravity, an indicator of edema formation, was examined in dec apitated animals at corresponding time points. Brain injury induced si gnificant increases of ODC in the ipsilateral hippocampus, adjacent an d injury-site cortices, and in the contralateral cortex and hippocampu s at 3 and 6 h after injury. No significant edema formation was found in any brain region at 30 min after injury. A significant edema format ion was first found only in the injury-site cortex at 3 h after injury . At 6 and 24 h after injury, significant edema was found in ail regio ns ipsilateral to the injury-site. At 24 h after injury, significant b ut less severe edema was also found in the contralateral cortex and hi ppocampus. DFMO, an irreversible inhibitor of ODC, abolished the incre ase in ODC in all regions. It also attenuated edema formation in the a djacent cortex and in the contralateral cortex and hippocampus. These findings indicate that polyamines may play a role in posttraumatic bra in edema formation, particularly in important brain regions remote fro m the injury-site.