This study aims to evaluate the chronic effects of estrogen on microcirculation, inflammatory biomarkers, hormonal status, plasma viscosity and biochemical tests in postmenopausal obese women after three months of follow-up intervention.

Estrogens exert pleiotropic actions on the cardiovascular system through binding to estrogen receptors. Traditionally, estrogen receptors have been recognized as transcription factors regulating the expression of target genes, however, numerous studies have revealed rapid actions of estrogen in different systems, so-called 'extranuclear actions'. At this level, estrogen triggers rapid vasodilatation, exerts anti-inflammatory effects, regulates vascular cell growth and migration, and confers protection to cardiomyocytes. Our aims are to investigate estrogen´s chronic effects on microcirculation.

The study will assess the potential benefits of estrogens on: chronic low-grade inflammation, metabolic profile, microcirculation and blood rheology. Postmenopausal obese women will be randomly submitted to estrogen (transdermal 17-β-estradiol 1mg/day) or placebo therapy during three months in a double-blind fashion. At baseline and after intervention, nailfold videocapillaroscopy, laser-Doppler flowmetry and venous occlusion plethysmography, inflammatory biomarkers, hormonal status, metabolic profile, plasma viscosity and anthropometrical measures will be assessed in all subjects.

Inclusion Criteria:

• History of natural menopause defined by the absence of menses for at least 12 months and a serum concentration of FSH > 35 IU/L
• BMI between 27 to 34.9 kg/m²
• Non-smokers
• Not on use of any hormones or supplements for a minimum of 6 months prior to the study
• No absolute contraindications to the use of physiological replacement doses of estrogen

Exclusion Criteria:

• Renal disease, coronary or peripheral vascular diseases, haematologic or hepatic diseases
• Diabetes mellitus, glucose intolerance or altered fasting glucose