Cushing's syndrome has been recently compared to visceral-type obesity, since it is characterised by the accumulation of adipose tissue at a deep abdominal site, to the detriment of the subcutaneous adipose panniculus, and is associated with insulin-resistance and hyperlipemia. The aim of the present study was to evaluate the influence of glucocorticoid hormones on lipolytic activity (index of FFA mobilisation) and on lipoproteinlipase (LPL) activity (an index of the accumulation of triglycerides) in subcutaneous and perirenal adipose tissue in order to clarify the mechanisms involved in this type of accumulation in Cushing's syndrome. Five patients (4 F and 1 M) were included in the study, mean age 27.8 +/- 3.7 years and BMI 21.3 +/- 1.2 kg/m2; patients were hospitalised in the 2nd Surgical Clinic at the University of Padua and underwent surgery for secondary corticosurrenal hyperplasia with ACTH secreting hypophysial adenoma. Lipolytic activity in subcutaneous adipose tissue in these patients was significantly lower (p less than 0.05) than in control subjects, in particular after noradrenalin stimulation (p less than 0.01). No significant difference was observed when lipolytic activity in subcutaneous adipose tissue was compared to that one in perirenal tissue. LPL activity in subcutaneous adipose tissue did not reveal statistically significant differences compared to control subjects, although values were lower. A further decrease in LPL activity, which was not however significant, was observed in perirenal tissue in comparison to subcutaneous tissues in the same patients. The mean weight of adipocytes (ug) was slightly lower in subcutaneous adipose tissue compared to control subjects and even lower in perineal tissue in comparison to the subcutis in the same patients.(ABSTRACT TRUNCATED AT 250 WORDS)