LEPTIN AND THE HYPOTHALAMIC-PITUITARY-ADRENAL AXIS ACTIVITY IN WOMEN WITH DIFFERENT OBESITY PHENOTYPES

OBJECTIVE: Women with visceral obesity may have hyperactivity of the h ypothalamic-pituitary-adrenal (HPA) axis. Since glucocorticoids are in volved in the expression of the ob gene, this study was carried out to investigate the relationship between serum leptin and the activity of the HPA axis in women with different obesity phenotypes. DESIGN: Cros s sectional clinical study. SUBJECTS: Fifteen obese (Body Mass Index B MI28 kg/m(2)) women and ten normal weight control women (BMI26 kg/m(2) ) were included in the study. MEASUREMENTS: Body fat distribution was defined by CT scan at the L4-L5 level. Baseline blood samples were obt ained for hormone concentrations. The activity of the HPA axis was eva luated by measuring ACTH and cortisol blood levels after combined iv a dministration of corticotropin releasing factor (100 mu g) + arginine- vasopressin (0.3 IU). RESULTS: Baseline cortisol, ACTH, and androgen l evels were similar in all groups, whereas leptin levels were significa ntly higher in the obese groups than in normal weight controls, withou t any significant difference between women with different obesity phen otypes. Incremental areas of ACTH and cortisol were significantly high er in women with visceral obesity than in those with subcutaneous obes ity and controls. No significant correlation was found between the act ivity of the HPA axis and leptin concentrations. Leptin showed a highl y significant correlation with BMI and subcutaneous fat and a weak but significant correlation with visceral fat and the visceral-to-subcuta neous fat ratio. CONCLUSION: Women with different obesity phenotypes h ad similar serum leptin concentrations but different HPA axis activity , and there was no correlation between them.