Reactions of granular pericytes in a rabbit cerebrovascular ischemia model.

Abstract

This study was undertaken to examine some of the quantitative and qualitative changes which might occur in the cerebral granular pericyte population when comparing control and embolically stressed animals. Eight animals, male NZW 2-2.5 kg rabbits, were given intracarotid sublethal injections of human atheroma concentrated at 125 mg/ml. Eight others received 1 cc of sterile saline. Two hours after injection the brains were fixed with either neutral buffered formalin or 3% buffered glutaraldehyde by cardiac perfusion at 110 mmHg pressure. The brains were removed and sliced, anteroposteriorly, in 3 mm slices. Each slice from five brains for each condition was then processed for paraffin sectioning and staining with Hematoxylin and PAS. Two animals for each condition underwent the same treatments and were processed for frozen sectioning and staining with Oil Red O. One animal for each condition had each brain slice sectioned by vibratome (40 micrometers) and was processed appropriately and examined by either fluorescence microscopy, standard electron microscopy or acid phosphatase electron microscopy. In the groups stained with Hematoxylin and PAS, granular pericytes were counted for each of the first five levels of each brain for both the control and experimental conditions. The results of this study reconfirmed that these cells were granular pericytes; that is, they were autofluorescent and PAS positive; were surrounded by a basement membrane, were acid phosphatase positive and contained a heterogenous granular cytoplasmic inclusion population. Further, after ischemic insult, the number of granular pericytes increased significantly at two hours. It was also shown that these cells appeared capable of accumulating lipid components of the injected atheroma from the vessel lumen.