RAGE mediates vascular injury and inflammation after global cerebral ischemia

Activation of receptor for advanced glycation end products contributes to aortic remodeling and endothelial dysfunction in sinoaortic denervated rats

OBJECTIVE

The aim of present study was to test the hypothesis that activation of receptor for advanced glycation end products (RAGE) pathway contributes to aortic remodeling and endothelial dysfunction in sinoaortic denervated (SAD) rats.

METHODS AND RESULTS

Experiment 1: 8 weeks after sinoaortic denervation, aortas were removed for measurement of AGE/RAGE pathway. Sinoaortic denervation in rats resulted in enhanced activity of aldose reductase, reduced activity of glyoxalase 1, accumulation of methylglyoxal and AGE, and upregulated expression of RAGE in aortas. Experiment 2: 5 weeks after sinoaortic denervation, the rats received intraperitoneal injections of 500 μg soluble RAGE (sRAGE) daily for 3 weeks. Treatment of SAD rats with sRAGE attenuated aortic remodeling, marked by reduction in AW/length, wall thickness, proliferation of SMC, and collagen deposition, and improvement of endothelial function. Treatment of SAD rats with sRAGE abated aortic oxidative stress, marked by reduction in formation of malondialdehyde, reactive oxygen species, superoxide, peroxynitrite and 3-nitrotyrosine, and enhancement of ratio of GSH/GSSG. Treatment of SAD rats with sRAGE attenuated aortic mitochondrial dysfunction. Treatment of SAD rats with sRAGE suppressed aortic NFκB nuclear translocation and inflammation. Treatment of SAD rats with sRAGE restored aortic NO formation through upregulating eNOS and dimethylarginine dimethylaminohydrolase-2 and downregulating protein arginine methyltransferase-1.

CONCLUSION

Activated RAGE contributed to aortic remodeling and endothelial dysfunction in SAD rats, possibly via induction of oxidative stress and inflammation, impairment of mitochondrial function, and reduction in NO bioavailability.

Ischemia-induced hyperglycemia: consequences, neuroendocrine regulation, and a role for RAGE

Many patients that present with cerebral ischemia exhibit moderate to severe hyperglycemia. Although many hyperglycemic patients suffer from diagnosed or previously undiagnosed diabetes a further subset of individuals is hyperglycemic without diabetes. Hyperglycemia during cerebral ischemia is associated with high levels of mortality and morbidity and limits the effective treatment interventions available. Controlling hyperglycemia with insulin treatment in critical care situations improves overall outcomes, although it is not without risk. Therefore it is critically important to understand the basic mechanisms that underlie both the induction of hyperglycemia and the consequences of it for ischemic outcomes. In this manuscript, the neuroendocrine mediators, and mechanisms of hyperglycemia exacerbated inflammation, glucose dysregulation and ischemic outcomes are discussed. The possibility that the advanced glycation end product (AGE) and receptor for AGE (RAGE) axis mediates the deleterious effects of hyperglycemia on inflammation and neuronal damage is discussed.