2-(2-nitro-1h-imidazol-1-yl)-n-(2-2-3-3-3-pentafluoropropyl)acetamide and Brain-Ischemia

The usefulness of hyperbaric oxygen (HBO) and normobaric hyperoxia in acute ischemic stroke is being reexplored because both improve outcome in experimental cerebral ischemia. However, even the basic mechanisms underlying oxygen therapy are poorly understood. We investigated the effect of both oxygen therapies on tissue hypoxia and on the transcription factor hypoxia-inducible factor-1 alpha.. Mice were subjected to filament-induced middle cerebral artery occlusion for 2 hours. Twenty-five minutes after filament introduction, mice breathed normobaric air, normobaric 100% O(2) (normobaric hyperoxia), or 100% O(2) at 3 ata (HBO) for 95 minutes. Hypoxic regions were mapped on tissue sections after preischemic infusion of the in vivo hypoxia marker EF-5. Hypoxia-inducible factor-1 alpha protein was measured after 2-hour middle cerebral artery occlusion using immunofluorescence and immunoblotting. Vascular endothelial growth factor expression was analyzed using in situ mRNA hybridization.. Severity of ischemia did not differ among groups. HBO (35.2+/-10.4 mm(2)) significantly reduced the area of EF-5-stained hypoxic regions in focal cerebral ischemia compared with normobaric hyperoxia (46.4+/-11.2 mm(2)) and air (49.1+/-8 mm(2), P<0.05, analysis of variance). Topographically, EF-5 fluorescence was decreased in medial striatum and in cortical ischemic border areas. Immunohistochemistry and immunoblotting revealed lower hypoxia-inducible factor-1 alpha protein in the ischemic hemisphere of HBO-treated mice. Moreover, mRNA in situ hybridization showed lower expression of vascular endothelial growth factor in HBO and normobaric hyperoxia groups.. Measurement of extrinsic and intrinsic markers of hypoxia revealed that HBO improves penumbral oxygenation in focal ischemia. Modification of the transcription factor hypoxia-inducible factor-1 alpha and its downstream targets may be involved in effects of HBO.

Topics: Animals; Brain; Brain Ischemia; Cerebral Cortex; Corpus Striatum; Down-Regulation; Etanidazole; Fluorescent Antibody Technique; Hydrocarbons, Fluorinated; Hyperbaric Oxygenation; Hypoxia-Inducible Factor 1; Hypoxia, Brain; Indicators and Reagents; Infarction, Middle Cerebral Artery; Male; Mice; Mice, Inbred C57BL; Oxygen; Oxygen Consumption; RNA, Messenger; Staining and Labeling; Vascular Endothelial Growth Factor A

E2F1+/- mice subjected to 2 h middle cerebral artery occlusion developed an infarct of 77.0 +/- 3.2 mm3 (mean +/- s.e.m., n = 15) in the ischemic hemisphere after 24 h reperfusion. A significantly smaller infarct of 58.8 +/- 4.8 mm3 (n = 15; p < 0.01) was found in E2F1-/- animals. Both deficient and normal mice had similar cerebral angioarchitecture and intra-ischemic decreases in regional blood flow. Similar areas of hypoxia in both groups of ischemic animals were demonstrated directly by immunohistochemical detection of nitroimidazole adducts. It was concluded that all animals received the same ischemic insult, yet the subsequent damage was different in the mutant mice. This is the first indication that the E2F1 gene plays a role in ischemic death of post-mitotic neurons.

Topics: Animals; Brain Ischemia; Carrier Proteins; Cell Cycle Proteins; Cerebral Infarction; Cerebrovascular Circulation; DNA-Binding Proteins; E2F Transcription Factors; E2F1 Transcription Factor; Etanidazole; Hydrocarbons, Fluorinated; Hypoxia; Immunohistochemistry; Mice; Mice, Inbred C57BL; Mice, Inbred Strains; Retinoblastoma-Binding Protein 1; Transcription Factor DP1; Transcription Factors

Topics: Animals; Animals, Newborn; Antibodies, Monoclonal; Brain Ischemia; Colonic Neoplasms; Etanidazole; Humans; Hydrocarbons, Fluorinated; Hypoxia; Hypoxia, Brain; Immunohistochemistry; Male; Mice; Mice, Inbred C57BL; Mice, Nude; Myocardial Infarction; Rats; Rats, Sprague-Dawley; Transplantation, Heterologous; Tumor Cells, Cultured