ABSTRACT
Estrogen has direct effects within adipose tissue and has been implicated in regional adiposity; however, the influence of estrogen on in vivo lipolysis is unclear. The purpose of this study was to investigate the effect of local 17ß-estradiol (E(2)) on subcutaneous adipose tissue (SAT) lipolysis in premenopausal women. In vivo lipolysis (dialysate glycerol) was measured in 17 women (age 27.4 ± 2.0 yr, BMI 29.7 ± 0.5 kg/m(2)) via microdialysis of abdominal (AB) and gluteal (GL) SAT. Glycerol was measured at baseline and during acute interventions to increase lipolysis including local perfusion of isoproterenol (ISO, ß-adrenergic agonist, 1.0 µmol/l), phentolamine (PHEN, α-adrenergic antagonist, 0.1 mmol/l), and submaximal exercise (60% Vo(2peak), 30 min); all with and without coperfusion of E(2) (500 nmol/l). E(2) coperfusion blunted the lipolytic response to ISO in AB (E(2) 196 ± 31%, control 258 ± 26%, P = 0.003) but not in GL (E(2) 113 ± 14%, control 111 ± 12%, P = 0.43) adipose tissue. At rest, perfusion of PHEN with ISO did not change dialysate glycerol. Submaximal exercise during ISO + PHEN increased dialysate glycerol in the AB (56 ± 9%) and GL (62 ± 12%) regions. Probes perfused with E(2) during exercise and ISO + PHEN had an increased lipolytic response in AB (90 ± 9%, P = 0.007) but a lower response in GL (35 ± 7%, P = 0.05) SAT compared with no-E(2) conditions. E(2) effects on lipolysis are region specific and may work through both adrenergic and adrenergic-independent mechanisms to potentiate and/or blunt SAT lipolysis in premenopausal women.
