title: Effects of hypoxia-reoxygenation on rat blood-brain barrier permeability and tight junctional protein expression.
abstract: Cerebral microvessel endothelial cells that form the blood-brain barrier (BBB) have tight junctions (TJs) that are critical for maintaining brain homeostasis. The effects of initial reoxygenation after a hypoxic insult (H/R) on functional and molecular properties of the BBB and TJs remain unclear. In situ brain perfusion and Western blot analyses were performed to assess in vivo BBB integrity on reoxygenation after a hypoxic insult of 6% O2 for 1 h. Model conditions [blood pressure, blood gas chemistries, cerebral blood flow (CBF), and brain ATP concentration] were also assessed to ensure consistent levels and criteria for insult. In situ brain perfusion revealed that initial reoxygenation (10 min) significantly increased the uptake of [14C]sucrose into brain parenchyma. Capillary depletion and CBF analyses indicated the perturbations were due to increased paracellular permeability rather than vascular volume changes. Hypoxia with reoxygenation (10 min) produced an increase in BBB permeability with associated alterations in tight junctional protein expression. These results suggest that H/R leads to reorganization of TJs and increased paracellular diffusion at the BBB, which is not a result of increased CBF, vascular volume change, or endothelial uptake of marker. Additionally, the tight junctional protein occludin had a shift in bands that correlated with functional changes (i.e., increased permeability) without significant change in expression of claudin-3, zonula occludens-1, or actin. H/R-induced changes in the BBB may result in edema and/or associated pathological outcomes.
authors.affiliation: Department of Pharmacology, College of Medicine, University of Arizona, Tucson, AZ 85724, USA.
authors.forename: Ken A
authors.initials: KA
authors.lastname: Witt
authors.forename: Karen S
authors.initials: KS
authors.lastname: Mark
authors.forename: Sharon
authors.initials: S
authors.lastname: Hom
authors.forename: Thomas P
authors.initials: TP
authors.lastname: Davis
mesh_terms: D000199:Actins / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D001794:Blood Pressure; D001812:Blood-Brain Barrier / Q000502:physiology*; D001921:Brain / Q000033:anatomy & histology / Q000098:blood supply / Q000378:metabolism; D000440:Butanols / Q000493:pharmacokinetics; D002196:Capillaries / Q000502:physiology; D002245:Carbon Dioxide / Q000097:blood; D062465:Claudin-3; D004573:Electrolytes / Q000097:blood; D005260:Female; D000860:Hypoxia / Q000378:metabolism / Q000503:physiopathology; D002534:Hypoxia, Brain / Q000378:metabolism / Q000503:physiopathology*; D017078:Laser-Doppler Flowmetry; D008565:Membrane Proteins / Q000378:metabolism*; D009929:Organ Size; D010100:Oxygen / Q000097:blood; D010477:Perfusion; D010750:Phosphoproteins / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D019108:Tight Junctions / Q000378:metabolism*; D014316:Tritium; D062826:Zonula Occludens-1 Protein
chemical_list: D000199:Actins; D000440:Butanols; D062465:Claudin-3; C568124:Cldn3 protein, rat; D004573:Electrolytes; D008565:Membrane Proteins; D010750:Phosphoproteins; C569044:Tjp1 protein, rat; D062826:Zonula Occludens-1 Protein; D014316:Tritium; D002245:Carbon Dioxide; D000255:Adenosine Triphosphate; D010100:Oxygen