A reduction in plasma triglyceride concentrations was observed in postmenopausal women after estradiol treatment but not progesterone or testosterone, according to research in The Journal of Clinical Endocrinology & Metabolism, shedding light on the sexual dimorphism in metabolizing the cholesterol component.
In a study at the Washington University School of Medicine in St. Louis, 27 women in their postmenopausal years who were sedentary (<1.5 hours of exercise each week) and weight stable (<2 kg change for at least 6 months) were evaluated for very LDL-triglyceride (VLDL-TG) concentration and kinetics before and after treatments of sex steroids.
Gordon I. Smith, PhD, and colleagues examined blood samples from four cohorts — 17 beta-estradiol (0.1 mg/day via continuous delivery skin patch); progesterone (100 mg/day via vaginal insert), testosterone (12.5 mg/day via skin gel); or no intervention — using stable-isotope labeled tracer techniques to determine plasma glucose, insulin, free-fatty acids and VLDL-TG.
Analysis showed estradiol treatment reduced VLDL-TG concentration by approximately 30% due to accelerated VLDL-TG plasma clearance (25.1 ± 2.5 mL/minute vs. 17.4 ± 2.7 mL/minute; P<.01). Concentration and kinetics of VLDL-TG remained unchanged in the control group and unaltered by treatment with testosterone or progesterone.
“The stimulatory effect of estradiol on VLDL-TG plasma clearance helps explain the lower plasma TG concentration in women compared with men,” the researchers wrote. “However, it is unlikely that estradiol availability is the sole factor involved in the sexually dimorphic plasma TG metabolism phenotype because it only partially explains the differences in VLDL-TG kinetics between men and women, most likely due to a complex interplay of multiple regulatory factors.”
Disclosure: This study was supported by multiple grants from the NIH.