Benefit from testosterone and hydrocortisone on coronary atherogenesis in cockerels on a low protein atherogenic diet

Modulation of 11β-hydroxysteroid dehydrogenase as a strategy to reduce vascular inflammation

Atherosclerosis is a chronic inflammatory disease in which initial vascular damage leads to extensive macrophage and lymphocyte infiltration. Although acutely glucocorticoids suppress inflammation, chronic glucocorticoid excess worsens atherosclerosis, possibly by exacerbating systemic cardiovascular risk factors. However, glucocorticoid action within the lesion may reduce neointimal proliferation and inflammation. Glucocorticoid levels within cells do not necessarily reflect circulating levels due to pre-receptor metabolism by 11β-hydroxysteroid dehydrogenases (11β-HSDs). 11β-HSD2 converts active glucocorticoids into inert 11-keto forms. 11β-HSD1 catalyses the reverse reaction, regenerating active glucocorticoids. 11β-HSD2-deficiency/inhibition causes hypertension, whereas deficiency/inhibition of 11β-HSD1 generates a cardioprotective lipid profile and improves glycemic control. Importantly, 11β-HSD1-deficiency/inhibition is atheroprotective, whereas 11β-HSD2-deficiency accelerates atherosclerosis. These effects are largely independent of systemic risk factors, reflecting modulation of glucocorticoid action and inflammation within the vasculature. Here, we consider whether evidence linking the 11β-HSDs to vascular inflammation suggests these isozymes are potential therapeutic targets in vascular injury and atherosclerosis.

Therapeutic manipulation of glucocorticoid metabolism in cardiovascular disease

The therapeutic potential for manipulation of glucocorticoid metabolism in cardiovascular disease was revolutionized by the recognition that access of glucocorticoids to their receptors is regulated in a tissue-specific manner by the isozymes of 11beta-hydroxysteroid dehydrogenase. Selective inhibitors of 11beta-hydroxysteroid dehydrogenase type 1 have been shown recently to ameliorate cardiovascular risk factors and inhibit the development of atherosclerosis. This article addresses the possibility that inhibition of 11beta-hydroxsteroid dehydrogenase type 1 activity in cells of the cardiovascular system contributes to this beneficial action. The link between glucocorticoids and cardiovascular disease is complex as glucocorticoid excess is linked with increased cardiovascular events but glucocorticoid administration can reduce atherogenesis and restenosis in animal models. There is considerable evidence that glucocorticoids can interact directly with cells of the cardiovascular system to alter their function and structure and the inflammatory response to injury. These actions may be regulated by glucocorticoid and/or mineralocorticoid receptors but are also dependent on the 11beta-hydroxysteroid dehydrogenases which may be expressed in cardiac, vascular (endothelial, smooth muscle) and inflammatory (macrophages, neutrophils) cells. The activity of 11beta-hydroxysteroid dehydrogenases in these cells is dependent upon differentiation state, the action of pro-inflammaotory cytokines and the influence of endogenous inhibitors (oxysterols, bile acids). Further investigations are required to clarify the link between glucocorticoid excess and cardiovascular events and to determine the mechanism through which glucocorticoid treatment inhibits atherosclerosis/restenosis. This will provide greater insights into the potential benefit of selective 11beta-hydroxysteroid dehydrogenase inhibitors in treatment of cardiovascular disease.

Sex hormones and metabolism of glycosaminoglycans. I. Effect of orchidectomy and administration of testosterone in rabbits

The effect of orchidectomy in male rabbits and administration of testosterone to orchidectomized animals on the metabolism of glycosaminoglycans (GAG) has been studied. The response of the different GAG fractions in the aorta varies with the nature of the GAG, and in some cases is different in different segments of the aorta. Orchidectomy produced an increase in hyaluronic acid fraction, decrease in heparin sulphate fraction, and no response in the chondroitin sulphate A fraction in the aortic arch, thoracic aorta, and abdominal aorta. Chondroitin sulphate C and chondroitin sulphate B fractions decreased only in the abdominal aorta and were not significantly altered in the other two segments, while heparin fraction decreased only in the thoracic aorta and was not affected in the other segments. Administration of testosterone to the orchidectomized animals counteracted these changes in the aortic GAG fractures. The enzymes concerned with the synthesis of precursors of GAG--L-glutamine:D-fructose-6-phosphate aminotransferase, UDPG dehydrogenase, and UDPG pyrophosphorylase-- all decreased in the orchidectomized animals; testosterone administration increased their activity in the orchidectomized animals. Enzymes concerned with degradation of GAG--beta-glucuronidase, beta-hexosaminidase, aryl sulphatase, cathepsin, and hyaluronidase--increased in the orchidectomized and decreased on administration of testosterone. Concentration of PAPS and activity of sulphate-activating system and sulphotransferase also decreased in the orchidectomized animals, and testosterone administration tended to restore this decrease to normal levels.