Histopathologic and neurobehavioral evaluation of a standardized fluid percussion model of brain trauma in the rat

Abstract

For 5 male Sprague Dawley rats/group: Group 1 had a craniotomy; Group 2 had a craniotomy with a temporary luer lock fitting applied; and Group 3 additionally had a fluid percussive injury of approximately 5.5 atmospheres through the temporary luer lock to the exposed right lateral cerebral cortex. The skull defect was closed and behavioral assessments were performed at 2 hours after recovery from anesthesia, and again on Days 1, 3 and 14 post insult. The group given fluid percussion had deficits on balance beam, catalepsy and startle responses on day 0 that resolved at later timepoints. After 2 weeks, rats were euthanized under anesthesia and their brains were perfused in situ. Brains were trimmed at 2 mm intervals. Tissue loss at the cerebral cortical surface was estimated from H&E-stained sections using an ocular grid and averaged 2.3,1.9, and 6.1 mm2 respectively. In addition to greater loss of cerebral cortical tissue, the fluid percussion group had focal gliosis in the white matter, and focal neuronal degeneration visible with Fluoro Jade B staining in the deep cortex ventral and lateral to the site, as well as increased GFAP staining in the ipsilateral dorsal thalamus. Perl's stain showed traces of iron consistent with previous hemorrhage at the site in all groups and in the deeper areas of gliosis in Group 3.