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A photothrombotic ring stroke model in rats with or without late spontaneous reperfusion in the region at risk
Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Medicine.
Umeå University, Faculty of Medicine, Department of Medical Biosciences, Pathology.
Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Medicine.
Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Medicine.
1999 (English)In: Brain Research, ISSN 0006-8993, E-ISSN 1872-6240, Vol. 849, no 1-2, p. 175-186Article in journal (Refereed) Published
Abstract [en]

This study aimed at developing a dual setup of the photothrombotic ring stroke model with or without late spontaneous reperfusion in the region at risk and to explore the morphological consequences. The exposed crania of adult male Wistar rats were subjected to a ring-shaped laser-irradiation beam (o.d. 5.0 mm, 0.35 mm thick) for 2 min simultaneously with intravenous erythrosin B (17 mg/kg) infusion. Transcardial carbon-black perfusion revealed that a laser intensity of 0.90 W/cm(2) resulted in late, that is, starting at 72 h, spontaneous reperfusion, whereas the lowest laser intensity that produced lack of reperfusion at 7 days post-irradiation was 1.84 W/cm(2). Laser-Doppler flowmetry showed prompt cortical cerebral blood flow (cCBF) reduction both in the ring lesion and region at risk (12% and 25% of control values) after high-intensity irradiation; these reduced flow values were more rapid and pronounced than in the low-intensity irradiation setup as previously shown. The high- compared with low-intensity irradiation setup produced more frequent occurrence of thrombi in the ring-lesion region and a larger ischemic cortical lesion with a more rapid pace of ischemic cellular changes in the ring-lesion region and the region at risk. The region at risk transformed into pannecrosis in the high-intensity, but recovered morphologically in the low-intensity irradiation setup. This dual photothrombotic setup with or without spontaneous reperfusion enables the study of events related to ischemic cell survival or death in an anatomically predefined region at risk.

Place, publisher, year, edition, pages
1999. Vol. 849, no 1-2, p. 175-186
National Category
Neurosciences
Identifiers
URN: urn:nbn:se:umu:diva-133949DOI: 10.1016/S0006-8993(99)02152-6ISI: 000084486900019PubMedID: 10592300Scopus ID: 2-s2.0-0345008870OAI: oai:DiVA.org:umu-133949DiVA, id: diva2:1090132
Available from: 2017-04-22 Created: 2017-04-22 Last updated: 2019-03-19Bibliographically approved
In thesis
1. Apoptotic and necrotic cell death after photothrombotic ring stroke: characterization of a stroke model and its morphological and molecular consequences
Open this publication in new window or tab >>Apoptotic and necrotic cell death after photothrombotic ring stroke: characterization of a stroke model and its morphological and molecular consequences
2003 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Cerebral ischemic cell death is a major cause of disability and death among stroke patients. The brain cell demise can occur through apoptosis or necrosis or as a continuum of both. This study aimed at establishing a dual setup of a photothrombotic ring stroke model and exploring its morphological and molecular consequences.

    Photothrombotic ring stroke was induced in adult male Wistar rats by a ring shaped laser irradiation beam (514.5nm, outer diameter 5mm, thickness 0.35 mm) for 120 seconds focused on the exposed intact skull bone with simultaneous intravenous infusion of the photosensitizer erythrosin B (17 mg/kg). By using otherwise identical experimental conditions, high intensity irradiation (1.94 W/cm2) resulted in consistent lack of reperfusion in the region at risk whereas low intensity irradiation (0.90 W/cm2) induced late spontaneous reperfusion. The morphological appearance of apoptotic and necrotic cells was demonstrated by H&E, TUNEL and Hoechst stainings under light microscopy, immunohistochemistry and electron microscopy. This was further confirmed by gel electrophoresis showing DNA laddering that coexisted with DNA smear. Cell counts revealed that apoptotic cells appeared earlier (at 24 h) and remained as long as the necrotic cells, that is up to 72 hours after ischemic onset in regions with severe CBF reduction. After low intensity irradiation, we observed early and widespread increased expression of the anti-apoptotic protein bcl-w and a prolonged elevation of Bcl-2 with unchanged pro-apoptotic Bax in mitochondria. In contrast, decreased bcl-w and Bcl-2 with scattered Bax remained after high intensity irradiation. Correspondingly, the release of the pro-apoptotic factor Smac/DIABLO from the mitochondria to the cytosol was more persistent in high- compared with low-intensity irradiation.   

    Apoptotic and necrotic cell death coexisted in the same regions at the same time after photothrombotic ring stroke induced by low- or high-intensity irradiation, where spontaneous morphological recovery or pannecrosis were evident in the region at risk. The ratios between Bcl-w, Bcl-2 and Bax may direct the translocation of Smac/DIABLO from the mitochondria to the cytosol and thereby influence cell death or survival after focal cerebral ischemia.

Place, publisher, year, edition, pages
Umeå: Umeå University, 2003. p. 59
Series
Umeå University medical dissertations, ISSN 0346-6612 ; 826
National Category
Medical and Health Sciences Neurosciences
Identifiers
urn:nbn:se:umu:diva-133950 (URN)91-7305-390-2 (ISBN)
Public defence
2003-02-28, Sal B, plan 9, By 1D, NUS, Umeå, 13:00 (English)
Opponent
Supervisors
Available from: 2019-03-19 Created: 2017-04-22 Last updated: 2019-03-21Bibliographically approved

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Hu, XiaoLeiBrännström, ThomasGu, WeigangWester, Per

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