Reduced adipose glucocorticoid reactivation and increased hepatic glucocorticoid clearance as an early adaptation to high-fat feeding in Wistar rats.
Altered peripheral glucocorticoid metabolism may be important in the pathogenesis of obesity in humans and animal models. Genetically obese Zucker rats, Lep/ob mice, and obese humans exhibit increased regeneration of active glucocorticoids selectively in adipose tissue by 11beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD-1) and increased glucocorticoid clearance by hepatic A-ring reductases. We have examined whether dietary obesity in rats induces the same changes in glucocorticoid metabolism. Male Wistar rats were weaned onto high-fat (HF; 45% kcal from fat) or control (10% fat) diets. After 3 wk, HF rats showed no differences in weight but were glucose intolerant, had lower 11beta-HSD-1 activity in liver (3.8 +/- 0.2 vs. 4.9 +/- 0.2 pmol product/min.mg protein; P <0.01), sc fat (0.03 +/- 0.01 vs. 0.09 +/- 0.01 pmol product/min.mg protein; P <0.01), and omental fat (0.02 +/- 0.001 vs. 0.03 +/- 0.003 pmol/ product/min.mg protein; P <0.05) and higher hepatic 5beta-reductase activity (0.26 +/- 0.05 vs. 0.10 +/- 0.007 pmol product/min.mg protein; P <0.05). After 20 wk, HF rats were obese, hyperglycemic, and hyperinsulinemic, but differences in 11beta-HSD-1 and 5beta-reductase activities were no longer apparent. Mature male rats given HF diets for 24 or 72 h showed increased hepatic 5beta-reductase activity and a trend for decreased sc adipose 11beta-HSD-1 activity. Dietary obesity is not accompanied by the changes in 11beta-HSD-1 and 5beta-reductase expression and activity observed in genetically obese rodents. Acute exposure to HF diet alters glucocorticoid metabolism, predicting lower hepatic and adipose intracellular glucocorticoid concentrations, which may be a key mechanism protecting against the metabolic complications of obesity.
Drake
Amanda J
AJ
Endocrinology Unit, School of Molecular and Clinical Medicine, University of Edinburgh, Molecular Medicine Centre, Western General Hospital, Edinburgh EH4 2XU, United Kingdom. mandy.drake@ed.ac.uk
Livingstone
Dawn E W
DE
Andrew
Ruth
R
Seckl
Jonathan R
JR
Morton
Nicholas M
NM
Walker
Brian R
BR
D043205:11-beta-Hydroxysteroid Dehydrogenase Type 1 / Q000235:genetics / Q000378:metabolism; D013741:3-Oxo-5-alpha-Steroid 4-Dehydrogenase / Q000235:genetics / Q000378:metabolism; D000222:Adaptation, Physiological / Q000502:physiology; D000273:Adipose Tissue / Q000378:metabolism*; D000818:Animals; D001823:Body Composition; D004041:Dietary Fats / Q000494:pharmacology*; D004435:Eating / Q000502:physiology*; D005260:Female; D005938:Glucocorticoids / Q000378:metabolism*; D007030:Hypothalamo-Hypophyseal System / Q000502:physiology; D007333:Insulin Resistance; D008099:Liver / Q000378:metabolism*; D009765:Obesity / Q000378:metabolism / Q000503:physiopathology*; D051381:Rats; D017208:Rats, Wistar
D004041:Dietary Fats; D005938:Glucocorticoids; D043205:11-beta-Hydroxysteroid Dehydrogenase Type 1; D013741:3-Oxo-5-alpha-Steroid 4-Dehydrogenase