Glycerol attenuates the adherence of leukocytes in rat pial venules after transient middle cerebral artery occlusion

Intravenous infusion of glycerol has been used in patients with a cerebral infarction, expecting improvement in brain edema and cerebral blood flow (C BF). However, the mechanism of the improvement of CBF has not been clearly demonstrated. The aim of this study in the rat pial microvasculature after transient middle cerebral artery occlusion (MCAO) is to examine the effects of glycerol on leukocyte-endothelium interaction, which plays a critical r ole in the pathogenesis of brain injury by ischemia/reperfusion and concern s induction of secondary brain damage. Rhodamine 6G-labeled leukocytes at t he brain surface were visualized with intra-vital fluorescence videomicrosc opy through a closed cranial window and an analysis was made of the number of adherent leukocytes and the centerline leukocyte velocity in the venule before MCAO, after reperfusion of MCAO and after infusion of glycerol (Grou p 1) or saline (Group 2). The number of adherent leukocytes decreased and t he centerline leukocyte velocity increased statistically significantly imme diately after the infusion of glycerol in Group 1, but there was no signifi cant change in Group 2. The infusion of glycerol washes away the adherent l eukocytes and prevents them from interfering with the blood cell and plasma flow Furthermore, secondary brain damage may be relieved by decreasing the adherence of leukocytes. In conclusion, modulating the adherence of leukoc ytes is one of the important factors in the neuroprotective effect of glyce rol.