Effects of testosterone and estrogen treatment on lipolysis signaling pathways in subcutaneous adipose tissue of postmenopausal women

Abstract

The aim of this study was to investigate the treatment effects of testosterone and estrogen on the expression of proteins and genes involved in adipocyte signal transduction to lipolysis in abdominal subcutaneous adipose tissue of postmenopausal women. An open, randomized clinical study with parallel group comparison. Women's health clinical research unit and a research laboratory at a university hospital. Thirty-six healthy naturally postmenopausal women. The participants were randomly given testosterone undecanoate (40 mg every second day) or estradiol valerate (2 mg daily) for 3 months. Expression of proteins and genes involved in adipocyte signal transduction to lipolysis in abdominal subcutaneous adipose tissue, determined by quantitative real-time polymerase chain reaction and Western blot, respectively, and related to plasma glycerol before or during a euglycemic hyperinsulinemic clamp. Testosterone treatment decreased the expression of hormone-sensitive lipase and increased the expression of phosphodiesterase-3B, whereas no effect of estrogen was observed. Testosterone-induced changes in hormone-sensitive lipase expression correlated positively with corresponding changes in basal or clamp-induced plasma glycerol concentrations. Treatment with testosterone in postmenopausal women down-regulates hormone-sensitive lipase and up-regulates phosphodiesterase-3B expressions in abdominal subcutaneous adipose tissue in relation to changes in vivo of lipolytic activity, which may promote the accumulation of fat.