Carbenoxolone treatment attenuates symptoms of metabolic syndrome and atherogenesis in obese, hyperlipidemic mice

Abstract

Glucocorticoids, which are well established to regulate body fat mass distribution, adipocyte lipolysis, hepatic gluconeogenesis, and hepatocyte VLDL secretion, are speculated to play a role in the pathology of metabolic syndrome. Recent focus has been on the activity of 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1), which is capable of regenerating, and thus amplifying, glucocorticoids in key metabolic tissues such as liver and adipose tissue. To determine the effects of global 11β-HSD1 inhibition on metabolic syndrome risk factors, we subcutaneously injected “Western”-type diet-fed hyperlipidemic mice displaying moderate or severe obesity [LDL receptor (LDLR)-deficient (LDLR−/−) mice and mice derived from heterozygous agouti ( Ay/a) and homozygous LDLR−/−breeding pairs ( Ay/a;LDLR−/−mice)] with the nonselective 11β-HSD inhibitor carbenoxolone for 4 wk. Body composition throughout the study, end-point fasting plasma, and extent of hepatic steatosis and atherosclerosis were assessed. This route of treatment led to detection of high levels of carbenoxolone in liver and fat and resulted in decreased weight gain due to reduced body fat mass in both mouse models. However, only Ay/a;LDLR−/−mice showed an effect of 11β-HSD1 inhibition on fasting insulin and plasma lipids, coincident with a reduction in VLDL due to mildly increased VLDL clearance and dramatically decreased hepatic triglyceride production. Ay/a;LDLR−/−mice also showed a greater effect of the drug on reducing atherosclerotic lesion formation. These findings indicate that subcutaneous injection of an 11β-HSD1 inhibitor allows for the targeting of the enzyme in not only liver, but also adipose tissue, and attenuates many metabolic syndrome risk factors, with more pronounced effects in cases of severe obesity and hyperlipidemia.