title: Characteristics of sustained blood-brain barrier opening and tissue injury in a model for focal trauma in the rat.
abstract: Minor stab wounding of rodent brain by needle or razor blade is a standard model for immunohistochemical investigations of secondary neuronal degeneration and scarring. Opening of the blood-brain barrier (BBB) to plasma molecules and inflammatory cells is integral to the secondary injury process. To facilitate quantitative study of these BBB phenomena, we tested the utility of a stereotaxic wire knife as a minimally invasive way for modeling of focal trauma and bleeding in brain parenchyma and substantial, reproducible BBB damage. Adult rats were anesthetized, and through a skull burr hole, the 0.3-mm dia guide cannula housing a laterally extendable tungsten wire (0.13 mm dia) was inserted into the right striatum. A layering of horizontal disk-like cuts (3 mm dia) was made, producing a cylindrical lesion of approximately 18 mm3 volume, approximately 2.7% of the cerebral hemisphere. Transfer constants (Ki) for blood to brain permeation of [3H]sucrose measured from 30 min to 2 weeks postlesion showed sustained BBB leakiness; for example, mean Ki +/- SEM (nL.g(-1) x s(-1)) for a standard, matrix-dissected forebrain sample enclosing the lesion were 7.2 +/- 1.2 (day 1 postlesion), 8.1 +/-1.4 (day 3), 5.4 +/- 0.8 (day 14) compared with values for contralateral nonlesioned forebrain ranging from 1.3 +/- 0.05 to 1.6 +/- 0.3 (n = 3-4 samples per time point). Analysis of the simultaneous transport of [14C]sucrose (MW = 342 Da) and [3H]inulin (MW approximately 5,000) showed significantly larger upward increments in Ki for sucrose than inulin, indicating a pore-like opening mechanism. Significant edema was measured 3 days postlesion. A reactive glial response was indicated by an increase in S100beta by 6 h and a glial scar forming around the lesion by 7 days. Secondary brain injury was indicated by a 10% loss of hemisphere mass, measured at 2 months. The wire knife enabled tailoring of interstitial trauma with a minimum of extraneous injury and supported reproducible measurements of sustained BBB injury using relatively few animals.
authors.affiliation: Institute for Biological Sciences, National Research Council of Canada, Ottawa, Ontario. ed.preston@nrc.ca
authors.forename: E
authors.initials: E
authors.lastname: Preston
authors.forename: J
authors.initials: J
authors.lastname: Webster
authors.forename: D
authors.initials: D
authors.lastname: Small
mesh_terms: D000818:Animals; D019771:Axotomy; D001812:Blood-Brain Barrier / Q000502:physiology*; D001921:Brain / Q000378:metabolism* / Q000473:pathology / Q000503:physiopathology; D001930:Brain Injuries / Q000150:complications* / Q000473:pathology / Q000503:physiopathology; D004195:Disease Models, Animal; D020300:Intracranial Hemorrhages / Q000378:metabolism* / Q000473:pathology / Q000503:physiopathology; D008297:Male; D017072:Neostriatum / Q000293:injuries / Q000473:pathology / Q000503:physiopathology; D009410:Nerve Degeneration / Q000209:etiology / Q000473:pathology / Q000503:physiopathology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D020127:Recovery of Function / Q000502:physiology; D013997:Time Factors