To be elucidated how NBO affects ROS production in the ischemic brain. Several oxidant enzyme systems, such as xanthine oxidase, mitochondrial respiratory chain and NADPH oxidase have been identified as important source of ROS in the brain and contribute to oxidative brain injury following cerebral ischemia and reperfusion [12,13]. Accumulating evidence from animal stroke studies suggests that Nox is strongly implicated in the oxidative damage to the neuronal tissue and the BBB in ischemic stroke [14-18]. NADPH oxidase was first found in phagocytes, which is assembled from a purchase Quinagolide (hydrochloride) membrane spanning flavocytochrome b558, composed of Nox2 (also called gp91phox) and p22phox and four cytosolic factors (p47phox, p67phox, p40phox, and Rac) that associate with the flavocytochrome to form an active enzyme [19]. Recently, several novel?2011 Liu et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.Liu et al. Medical Gas Research 2011, 1:22 http://www.medicalgasresearch.com/content/1/1/Page 2 ofhomologs of the catalytic, electron carrier component of NADPH oxidase (gp91phox or Nox2) have been described in a variety of nonphagocytic cells, including Nox1, Nox3, Nox4, Nox5, Duox1 and Duox2 [20]. Among these homologies, only Nox1, Nox2 and Nox4 are found in brain tissue, and Nox2 expression is abundant in glia cells and endothelial cells, two major cellular components of the BBB [21,22]. Deletion of Nox2 (or gp91phox) results in reduced BBB damage in mouse models of ischemic stroke [22-27]. Nox2-derived ROS can directly oxidize phospholipid bilayer membrane to result in membrane disruption [28]. It can also indirectly interfere with the barrier function of the BBB through ROS-mediated stimulation of VEGF, monocyte chemoattractant protein-1, and matrix metalloproteinase-9 (MMP-9) [29-32]. Our previous studies showed that NBO treatment resulted in parallel reductions in MMP-9 and gp91phox expression in ischemic neuronal tissue and microvessels [3,4,16,32]. However, it remains to clarify whether there is a causal link between Nox2 containing NADPH oxidase and MMP-9 induction in the ischemic brain and whether NBO protects the BBB through acting on Nox2. In this study, we addressed these important questions on a mouse model of middle cerebral artery occlusion (MCAO) by comparing BBB damage, MMP-9 induction and the changes in tight junction protein PubMed ID:https://www.ncbi.nlm.nih.gov/pubmed/28461585 claudin-5 and occludin between wild-type and gp91 phox knockout mice. In addition, we also determined whether NBO induces any additional changes to these parameters when gp91phox was genetically deleted.in this study showed typical tissue infarction in the MCA territory of TTC-stained sections, indicating successful MCAO.Normobaric hyperoxia treatmentWild-type and gp91phox knockout mice were randomly assigned to normoxic and NBO group. Five min after the onset of MCAO, mice were put into separated individual air-tight boxes which were ventilated (3 L/min) with medical air (21 O2) or a gas mixture of 95 O2 + 5 CO2 during the 90 min ischemia. This specific gas mixture was shown to be neuroprotective in our previous studies using a rat model of stroke [3,4,32].Measurement of BBB permeabilityMaterials and methodsMice model of focal cerebral ischemiaOne hour before the.