Pharmacological Evaluation of Adipose Dysfunction via 11β-Hydroxysteroid Dehydrogenase Type 1 in the Development of Diabetes in Diet-Induced Obese Mice with Cortisone Pellet Implantation

Signals from intracellular glucocorticoids (GCs) via 11 beta-hydroxysteroid dehydrogenase type 1 (11 beta-HSD1) in adipose tissues have been reported to serve as amplifiers leading to deterioration of glucose metabolism associated with obesity. To elucidate adipose dysfunction via 11 beta-HSD1 activation in the development of obesity-related diabetes, we established novel diabetic mice by implanting a cortisone pellet (CP) in diet-induced obesity (DIO) mice. Cortisone pellet-implanted DIO mice (DIO/CP mice) showed hyperglycemia, insulin resistance, hyperlipidemia, and ectopic fat accumulation, whereas cortisone pellet implantation in lean mice did not induce hyperglycemia. In DIO/CP mice, indexes of lipolysis such as plasma glycerol and nonesterified fatty acids (NEFAs) increased before hyperglycemia appeared. Furthermore, the adipose mRNA level of 11 beta-HSD1 was up-regulated in DIO/CP mice compared with sham-operated DIO mice. RU486 (mifepristone, 11 beta-[p-(dimethylamino)phenyl]-17 beta-hydroxy-17-(1-propynyl)estra-4,9-dien-3-one), a glucocorticoid receptor antagonist, decreased adipose mRNA levels of 11 beta-HSD1 as well as adipose triglyceride lipase. RU486 also improved plasma NEFA, glycerol, and glucose levels in DIO/CP mice. These results demonstrate that lipolysis in adipose tissues caused by GC activation via 11 beta-HSD1 serves as a trigger for diabetes with ectopic fat accumulation. Our findings also indicate the possibility of a vicious circle of GC signals via 11 beta-HSD1 up-regulation in adipose tissues, contributing to deterioration of glucose metabolism to result in diabetes. Our DIO/CP mouse could be a suitable model of type 2 diabetes to evaluate adipose dysfunction via 11 beta-HSD1.