Effect of transection on the blood-spinal cord barrier of the rat after isolation from descending sources.
The disruption of descending pathways and subsequent release of vasoactive neurotransmitters may contribute to the abnormal vascular permeability observed after spinal cord injury. Therefore, the relationship between disruption of long descending fiber tracts in the rat spinal cord and the development of blood-spinal cord barrier breakdown to the protein horseradish peroxidase (HRP) was evaluated. This was accomplished by first transecting the cord in order to deplete transmitter stores in the distal (caudal) segments. One month after this isolation procedure, a second transection was made several segments distal to the first transection. The axial distribution of barrier permeability to HRP was evaluated at both the light and electron microscopic levels in this 'isolated cord' preparation. Camera lucida drawings, delineating the distribution of tracer leakage in the spinal cord, were used to quantify the extent of protein extravasation. Vascular leakage of the tracer was identified as early as 1 h postinjury but was restricted to segments adjacent to the second transection. By 1 day after injury, protein extravasation was more marked, as compared to the earlier time points, and axial spread of barrier breakdown occurred along more distal vascular sites. Abnormal permeability to HRP was confirmed at the ultrastructural level where the protein was present within vesicles in the endothelium and the surrounding smooth muscle layer and basal lamina. The tracer was also identified in the cytoplasmic compartment of neurons and glia and within the adjacent extracellular space.
Noble
L J
LJ
Department of Neurology, Veterans Administration Medical Center, San Francisco, CA 94121.
Ellison
J A
JA
D000818:Animals; D006470:Hemorrhage / Q000378:metabolism / Q000503:physiopathology*; D006735:Horseradish Peroxidase / Q000493:pharmacokinetics; D008297:Male; D008854:Microscopy, Electron; D051381:Rats; D011919:Rats, Inbred Strains; D013118:Spinal Cord Diseases / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology*
D006735:Horseradish Peroxidase