Estradiol acutely inhibits whole body lipid oxidation and attenuates lipolysis in subcutaneous adipose tissue: a randomized, placebo-controlled study in postmenopausal women

Abstract

ContextEstradiol (E2) promotes and maintains the female phenotype characterized by subcutaneous fat accumulation. There is evidence to suggest that this effect is due to increased anti-lipolytic α2A-adrenergic receptors, but whether this requires long-term exposure to E2or is an immediate effect is not clear.ObjectiveTo study acute effects of a single dose (4 mg) of 17β-E2on regional and systemic lipolysis.MethodsSixteen postmenopausal women (age, 59±5 years; weight, 67±10 kg; and BMI, 24.8±2.9) were studied in a crossover design: i) placebo and ii) 4 mg E2. Basal and adrenaline-stimulated regional lipolysis was assessed by microdialysis and substrate oxidation rates by indirect calorimetry. Tissue biopsies were obtained to assess lipoprotein lipase activity and mRNA expression of adrenergic, estrogen, cytokine, and vascular reactivity receptors.ResultsAcute E2stimulation significantly attenuated catecholamine-stimulated lipolysis in femoral subcutaneous adipose tissue (interstitial glycerol concentration (micromole/liter) ANOVA time vs treatment interaction,P=0.01) and lipolysis in general in abdominal adipose tissue (ANOVA treatment alone,P<0.05). E2also reduced basal lipid oxidation ((mg/kg per min) placebo, 0.58±0.06 vs E2, 0.45±0.03;P=0.03) and induced a significantly higher expression of anti-lipolytic α2A-adrenergic receptor mRNA (P=0.02) in skeletal muscle tissue as well as an upregulation ofeNOS(NOS3) mRNA (P=0.02).ConclusionE2acutely attenuates the lipolytic response to catecholamines in subcutaneous adipose tissue, shifts muscular adrenergic receptor mRNA toward anti-lipolytic α2A-receptors, decreases whole body lipid oxidation, and enhances expression of markers of vascular reactivity.