Blood-Brain Barrier Permeability, Neutrophil Accumulation and Vascular Adhesion Molecule Expression after Controlled Cortical Impact in Rats: A Preliminary Study

Abstract

Previous studies in our laboratory have shown that controlled cortical impact (CCI) produces an acute inflammatory response in rat brain, including neutrophil accumulation and upregulation of cell adhesion molecules. The purpose of this study was to compare the time course of acute inflammation to blood-brain barrier (BBB) breakdown after (CCI) in rats. Methods: Male Wistar rats (n = 4-7/group) were subjected to CCI (2.5mm depth, 4m/s) and injected with Evans-blue dye (2%, 5ml/kg) at 30min, 3.5h, 7.5h, or 23.5h after trauma, 30min after dye injection rats were saline-perfused. BBB permeability was measured by spectrophotometric quantitation of Evans-blue in injured brain. Alternate cryostat sections from the anterior segment of the injured hemisphere were analyzed immunohistochemically for neutrophils (MoAb RP-3 vs rat neutrophils) or E-selectin (MoAb vs E-selectin). Neutrophils and E-selectin-positive blood vessels were quantitated by light microscopy in 100× cortical and hippocampal fields. Results and Conclusions: BBB breakdown was maximal early after CCI, whereas maximum E-selectin upregulation (8h) and neutrophil accumulation (24h) occurved later. Events other than acute inflammation initiate BBB permeability after CCI. Acute inflammation may contribute to BBB permeability at 4h to 24h after CCI.