Morphologische Untersuchungen zu Veränderungen der Blut-Rückenmark-Schranke nach Rückenmarksläsionen bei der Ratte

Abstract

Twenty-five male Sprague-Dawley rats received cryolesions on the spinal cord and the reactions of this CNS tissue with particular attention to the blood-spinal cord barrier were histologically, immunocytochemically and ultrastructurally investigated. Two non-operated animals and a non-cryolesioned "sham" -operated animal served as controls. The cryolesion was performed with a newly developed surgical technique placing a cooled metal cylinder, filled with liquid nitrogen onto the exposed spinal cord in the area of segment T8. At time points six hours, one day, three days, six days and fifteen days after operation, a total of 16 animals was sacrificed and perfused intracardially with lanthanum nitrate. This electron dense tracer allowed verifying ultrastructurally the permeability of the capillary endothelium and its tight junctions, which are considered to be the morphological correlate of the blood-CNS barrier. Light microscopic evaluation revealed well defined changes in axons and myelin sheaths of the white matter, both in the area of the cryolesion, and distal to it. The applied lesion technique preserved much of the gray matter, which is often destroyed or severely damaged by other techniques. Electron microscopy demonstrated an increase in pinocytosis vesicles in the endothelial cells, as a sign of compromised blood-spinal cord barrier, already 6 hours after surgery. This indication of an open barrier remained evident until day fifteen. Nine additional animals were sacrificed one day, three days, six days and fifteen days after cryolesion (one animal without a lesion served as a control) and perfused with Paraformaldehyde. Following fixation, the expression of the glucose transporter isoform 1 (GLUT-1) as a marker of a functional barrier was investigated immunocytochemically using a polyclonal rabbit Anti-GLUT-1 antibody. GLUT-1 controls the glucose transport across the physiological blood-CNS barrier, but is downregulated or absent in when the barrier is open. The capillary endothelium in the cryolesion showed reduced GLUT-1 expression throughout the post-surgery period. However, the endothelium of the distal lesion area re-expressed GLUT1 after fifteen days, although the pinocytosis analysis still indicated an open barrier. In addition, nuclear medicine imaging examination (PET) was carried out on one animal, demonstrating increased glucose turnover in the lesion area. This investigation should contribute to answer the question, whether from an improved animal model of spinal cord injury more conclusions on mechanisms and treatment of human paraplegia can be drawn. The identified phases of opening and closing of blood-spinal cord barrier with the associated cellular changes, might give some evidence for clinically diagnostic and therapeutic targets.

Die pdf-Fassung ist inhaltlich mit dem Original identisch. Lediglich auf Seite 9 wurden die Bilder des Glucosetransporters GLUT-1 aktualisiert, um das Strukturmodell des GLUT-1 ergänzt und alle Copyright-Vermerke angebracht. Die Bilder im Bildteil S. 61 ff. sind die gescannten Originale, die jedoch in der Grösse neu eingepasst wurden. Der Lebenslauf, der ohnehin nicht mehr aktuell ist, wurde gegenüber der gedruckten Fassung weggelassen. Soweit es sich bei den Bildern um Farbfotos handelte, sind diese jetzt auch in Farbe wiedergegeben. Die gedruckte Version enthielt nur SW-Bilder.