Sex- and depot-specific lipolysis regulation in human adipocytes : interplay between adrenergic stimulation and glucocorticoids

• The purpose of this investigation was to explore interactions between adrenergic stimulation, glucocorticoids, and insulin on the lipolytic rate in isolated human adipocytes from subcutaneous and omental fat depots, and to address possible sex diff erences. Fat biopsies were obtained from 48 nondiabetic subjects undergoing elective abdominal surgery. Lipolysis rate was measured as glycerol release from isolated cells and proteins involved in lipolysis regulation were assessed by immunoblots. Fasting blood samples were obtained and metabolic and infl ammatory variables were analyzed. In women, the rate of 8-bromo-cAMP- and isoprenaline-stimulated lipolysis was ~ 2- and 1.5-fold higher, respectively, in subcutaneous compared to omental adipocytes, whereas there was no diff erence between the two depots in men. Dexamethasone treatment increased the ability of 8-bromo-cAMP to stimulate lipolysis in the subcutaneous depot in women, but had no consistent eff ects in fat cells from men. Protein kinase A, Perilipin A, and hormone sensitive lipase content in adipocytes was not aff ected by adipose depot, sex, or glucocorticoid treatment. In conclusion, catecholamine and glucocorticoid regulation of lipolysis in isolatedhuman adipocytes diff ers between adipose tissue depots and also between sexes. These findings may be of relevance for the interaction between endogenous stress hormones and adipose tissue function in visceral adiposity and the metabolic syndrome.

Nyckelord

visceral

subcutaneous

adipose tissue

cAMP

dexamethasone

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