INCREASED PERMEABILITY OF CEREBRAL VESSELS TO HORSERADISH-PEROXIDASE INDUCED BY ISCHEMIA IN MONGOLIAN GERBILS

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  • 1 January 1976
    • journal article
    • research article
    • Vol. 35  (4) , 307-325
Abstract
Cerebral ischemia was induced by occlusion of the left common carotid artery in adult Mongolian gerbils. The period of occlusion was 3, 6 or 18 h. Horseradish peroxidase (HRP) was i.v. injected in animals with clear neurological signs 1 h after release of the clip. The HRP was allowed to circulate for 5 min. Fixation was carried out by perfusion with aldehydes. Tissue, incubated for peroxidatic activity, from the left side of the brain was treated for EM. During the postischemic period enhanced permeability was demonstrated in the brains of all animals. The amount of HRP transferred into the neuropil depended on the duration of ischemia. The gerbils with 18 h occlusion showed the greatest content. The cells comprising the neuropil adjacent to vessels were studied and the degree of the pathological changes described below was increased proportionally to the time period of occlusion. The intercellular spaces, often filled with peroxidase, were expanded and the astrocytes swollen, especially the endfeet. Sometimes the astrocytes were pervious to HRP. The neurons were also swollen, but to a lesser degree than the astrocytes. No endothelial cell damage was observed. Even 18 h of occlusion did not change the plasma membranes. The intercellular spaces were free of HRP from the 1st luminal to the 1st abluminal tight junction. The cytoplasm exhibited HRP-containing vesicles of various types and shapes. Some were freely situated; others were connected to the plasma membrane and then opened to the vessel lumen or to the basement membrane. Since no cell damage was demonstrated, and since no HRP was diffusely dispersed in the cytoplasm it is assumed that vesicles are responsible for the enhancement of the vesicular transport that normally occurs after i.v. injection of HRP.