RESUMO
OBJECTIVE: To investigate the circadian rhythmicity of adiponectin in patients with Cushing's syndrome and obesity, as well as in normal subjects. The effects of glucocorticoids, insulin and leptin on the secretion of adiponectin were also explored. METHODS: 15 patients with Cushing's syndrome and 10 with obesity as well as 9 normal subjects were recruited and their serum adiponectin, glucocorticoids, insulin and leptin levels were determined 6 times a day (8:00, 12:00, 16:00, 20:00, 24:00, 3:00). RESULTS: Circadian rhythmicity of adiponectin was not observed, but the adiponectin levels in patients with obesity were lower than those in the normal subjects at all 6 time spots. The area under curve (AUC) of serum adiponectin concentrations were significantly negatively correlated with body mass index (BMI, r = 0.46, P < 0.01), waist circumference (r = -0.33, P < 0.05) and insulin AUC (r = -0.36, P < 0.05). A multiple linear regression analysis revealed that BMI and waist circumference were two significant independent parameters of the plasma adiponectin level. The adiponectin levels did not manifest any change after short term dexamethasone administration with both high and low doses, but were obviously decreased after surgery. CONCLUSIONS: Neither long-term endogenous hyperglucocorticoidism nor short-term dexamethasone administration affects the serum adiponectin levels and the serum adiponectin concentrations remain unchanged even with elevated postprandial insulin levels.