EFFECTS OF RU-486 ON ENERGY-EXPENDITURE AND MEAL TOLERANCE IN NORMAL MEN

Objective: To evaluate the possible actions of glucocorticoids on rest ing energy expenditure and the thermogenic response to food in man. Me thods: The morning after administration of RU 486 or placebo, resting metabolic rate (RMR) and the thermogenic response to food (TRF), were measured after the ingestion of a standardized meal in 12 healthy male volunteers. Plasma glucose (PG) and insulin (PI) concentrations were also measured at regular intervals. Results: 1) After RU 486 administr ation, plasma cortisol was elevated throughout the test comparatively to placebo. 2) Fraction and concentration of free cortisol were also h igher after RU 486 than after placebo. 3) Corticosteroid-binding-globu lin (CBG) was similar in both experimentations. 4) RMR was not differe nt after RU 486 (1656 +/- 144 kcal/day) or after placebo (1632 +/- 120 kcal/day). 5) TRF was not different after RU 486 or placebo (54 +/- 1 2 kcal vs 59 +/- 13 kcal over a 6 hour period for RU 486 and placebo, respectively). 6) Baseline glucose concentrations were similar at base line but PG was higher 90 minutes postprandial with RU 486: 5.3 +/- 1. 7 mmol/L vs 3.7 +/- 0.8 mmol/L for placebo. 7) Plasma insulin was simi lar at baseline but it was significantly higher at 90 minutes postpran dial after RU 486 (347 +/- 143 vs 241 +/- 73 pmol/L for RU 486 and pla cebo, respectively). Conclusions: This study shows that acute inhibiti on of glucocorticoid action does not alter RMR and TRF in healthy men and that a mild deterioration of glucose tolerance follows the ingesti on of RU 486.