chondroitin-sulfates and Reperfusion-Injury

This study was undertaken to examine the mechanism by which danaparoid sodium (DS), a heparinoid that contains mainly heparan sulfate, prevents reperfusion-induced hepatic damage in a rat model of ischemia/reperfusion (I/R)-induced liver injury. Administration of DS significantly reduced liver injury and inhibited the decrease in hepatic tissue blood flow in rats. DS attenuated hepatic I/R-induced increases in hepatic tissue levels of tumor necrosis factor (TNF) and myeloperoxidase (MPO) in vivo. In contrast, neither monocytic TNF production nor neutrophil activation was inhibited by DS in vitro. DS enhanced I/R-induced increases in levels of calcitonin-gene related peptide (CGRP), a neuropeptide released from sensory neurons, and of 6-ketoprostaglandin (PG) F (1a) , a stable metabolite of PGI (2) , in liver tissues. The therapeutic effects of DS were not seen in animals pretreated with capsazepine, an inhibitor of sensory neuron activation. The distribution of heparan sulfate in the perivascular area was significantly increased by DS administration in this rat model. DS significantly increased CGRP release from isolated rat dorsal root ganglion neurons (DRG) in vitro, while DX-9065a, a selective inhibitor of activated factor X, did not. DS enhanced anandamide-induced CGRP release from DRG in vitro. These observations strongly suggested that DS might reduce I/R-induced liver injury in rats by attenuating inflammatory responses. These therapeutic effects of DS might be at least partly explained by its enhancement of sensory neuron activation, leading to the increase the endothelial production of PGI (2) .

Topics: Animals; Calcitonin Gene-Related Peptide; Chondroitin Sulfates; Dermatan Sulfate; Epoprostenol; Ganglia, Spinal; Heparitin Sulfate; Inflammation; Liver; Male; Neurons, Afferent; Rats; Rats, Wistar; Regional Blood Flow; Reperfusion Injury

This study examines the alteration of oligodendrocyte progenitor cells which express membrane NG2 chondroitin sulfate proteoglycan after focal ischemia in the rat brain. Adult male Sprague-Dawley rats were subjected to 90 min occlusion of the middle cerebral artery, followed by reperfusion time of up to 2 weeks. The distribution and morphological changes in NG2-positive oligodendrocyte progenitor cells were immunohistochemically examined. Stellate-shaped NG2-positive cells with multiple branched processes were detected in both the gray and white matter of normal brain. After 2 weeks of reperfusion, NG2-positive cells in the area surrounding the infarction site (peri-infarct area) clearly showed enlarged cell bodies with hypertrophied processes. These stained strongly for NG2. Although the number of NG2-positive cells was increased significantly in the peri-infarct area, it decreased markedly in the infarct core compared to controls. Double immunostaining revealed that these NG2-positive cells were neither astrocytes nor microglia, but NG2-positive oligodendrocyte progenitor cells. These progenitor cells are known to differentiate into oligodendrocytes. As such, this upregulation of NG2 expression may be an adaptive mechanism attempting to remyelinate rat brain tissue after ischemic insult. Only further study will elucidate this hypothesis.

Topics: Animals; Antigens; Brain Ischemia; Chondroitin Sulfates; Male; Oligodendroglia; Proteoglycans; Rats; Rats, Sprague-Dawley; Reperfusion Injury; Stem Cells

Heparin has long been established as an anticoagulant. Although heparin has been demonstrated to reduce brain injury after ischemia and reperfusion, its mechanism of action remains unknown. Recent investigations reveal that it can modulate biological processes such as binding to adhesion receptors on endothelial cells and leukocytes. The authors hypothesized that heparin's protective effect is closely related to its antileukocyte adherence property. They evaluated the efficacy of sulfated polysaccharides (unfractionated heparin, low-molecular-weight heparin, heparan sulfate, chondroitin sulfate C, and dextran sulfate) on leukocyte accumulation, infarction size, and neurological outcome after transient focal cerebral ischemia in rats subjected to 1 hour of ischemia and 48 hours of reperfusion. Forty-nine animals were included in the study. The animals receiving unfractionated heparin or dextran sulfate showed a significant reduction in leukocyte accumulation, infarct size, and neurological dysfunction 48 hours after reperfusion (p < 0.05) when compared to untreated animals. The animals receiving unfractionated heparin also showed significantly better results than the animals receiving an equivalent anticoagulant dose of low-molecular-weight heparin. These data indicate that heparin's antileukocyte property plays a more important role than its anticoagulant ability in neuronal protection. The relative potency of the sulfated polysaccharides tested in leukocyte depletion was closely related to their degree of sulfation. Thus, in addition to demonstrating the potential efficacy of heparin as a therapeutic agent for ischemia and reperfusion injury by the prevention of leukocyte accumulation, the results also serve as a basis for studying important cellular and molecular events that contribute to tissue damage.

Topics: Animals; Cell Adhesion; Chondroitin Sulfates; Dextran Sulfate; Heparin; Heparitin Sulfate; Ischemic Attack, Transient; Leukocytes; Male; Peroxidase; Rats; Rats, Sprague-Dawley; Reperfusion Injury

Although standard heparin has been demonstrated to reduce endothelial cell dysfunction in acute ischemia-reperfusion injury, its mechanism of action remains unknown. We hypothesized that heparin's salutary endothelial effects are independent of its conventional anticoagulant activity and are not caused by nonspecific polyanion effects.. Isolated rat hindlimbs were perfused at constant pressure with an albumin-enriched crystalloid buffer. After 60 minutes of normothermic ischemia, endothelial function was assessed by measurement of endothelial-dependent vasodilation by log increment infusion of acetylcholine. Endothelial-independent vasodilation was measured by exposure to nitroprusside. Some groups were pretreated with heparinoids possessing minimal or intermediate anticoagulant activity.. Treatment with heparinoids with low anticoagulant activity significantly increased endothelial-dependent vasodilation when compared with the nontreated ischemic group and were statistically indistinguishable from the nonischemic control. Treatment with dextran sulfate, a randomly sulfated polymer with size and charge characteristics similar to heparin, did not change postischemic vasodilation. Endothelial-independent vasodilation was largely unaffected by ischemia-reperfusion or drug treatment.. A heparinoid with negligible antithrombin-binding activity (Astenose) attenuated postischemic endothelial dysfunction, suggesting that its mechanism of action was independent of anticoagulant activity. Failure of dextran sulfate to be protective implied that the effect was not caused by nonspecific polyanion action.

Topics: Acute Disease; Animals; Anticoagulants; Chondroitin Sulfates; Dermatan Sulfate; Dextran Sulfate; Endothelium, Vascular; Heparin; Heparitin Sulfate; Hindlimb; In Vitro Techniques; Ischemia; Male; Rats; Rats, Sprague-Dawley; Reperfusion Injury; Vasodilation