Effects of estradiol on circulating P-selectin

Area of Science:

• Cardiovascular Science
• Endocrinology
• Hematology

Background:

• P-selectin mediates leukocyte adhesion to endothelial cells and activated platelets, playing a role in atherosclerosis.
• Soluble P-selectin (cP-selectin) levels are lower in premenopausal women than in men.
• 17 beta-estradiol (E2) exhibits antiatherogenic and cardioprotective effects.

Purpose of the Study:

• To investigate the hypothesis that E2 down-regulates P-selectin expression, thereby decreasing cP-selectin levels.
• To evaluate the impact of E2 on plasma cP-selectin levels in women throughout the menstrual cycle.
• To assess the effect of exogenous E2 administration on cP-selectin levels in men.

Main Methods:

• Studied 18 healthy women during their menstrual cycle to observe changes in serum E2 and cP-selectin.
• Administered a single intramuscular injection of 10 mg E2 valerate or placebo to 19 healthy male volunteers.
• Measured plasma cP-selectin levels before and after E2 or placebo administration in men.

Main Results:

• In women, increasing serum E2 concentrations correlated with a decrease in cP-selectin levels, with a maximum reduction of 13% in the luteal phase.
• In men, a single E2 injection significantly decreased cP-selectin levels by approximately 11% within 4 days.
• Baseline cP-selectin levels were approximately 30% higher in men compared to women during the midcycle and luteal phases.

Conclusions:

• E2 administration effectively lowers plasma cP-selectin levels in both women and men.
• The observed decrease in cP-selectin suggests reduced in vivo activation or damage of platelets and/or endothelial cells.
• This study identifies a potential novel mechanism contributing to the antiatherogenic and cardioprotective effects of E2 beyond its lipid-lowering properties.