Dehydroepiandrosterone-sulfate inhibits thrombin-induced platelet aggregation

Area of Science:

• Endocrinology
• Hematology
• Biochemistry

Background:

• Dehydroepiandrosterone (DHEA) and DHEA sulfate (DHEA-S) are abundant blood steroids.
• DHEA promotes nitric oxide release, which inhibits platelet responsiveness.
• The specific effects of DHEA-S on platelet function were previously uninvestigated.

Purpose of the Study:

• To investigate the impact of DHEA-S and DHEA on human platelet function.
• To determine if DHEA-S and DHEA modulate platelet responses to agonists.
• To elucidate the mechanisms underlying DHEA-S's effects on platelets.

Main Methods:

• In vitro studies using human platelets.
• Assays for platelet aggregation, dense granule secretion, and kinase activation (Akt, ERK1/2, p38 MAP kinase).
• Investigation of the cGMP/PGK/VASP pathway activation.

Main Results:

• DHEA-S, but not DHEA, dose-dependently inhibited thrombin-induced platelet aggregation.
• DHEA-S reduced thrombin-dependent dense granule secretion and impaired the ADP-mediated feedback loop.
• DHEA-S inhibited thrombin-induced activation of Akt, ERK1/2, and p38 MAP kinase.
• Both DHEA-S and DHEA activated the cGMP/PGK/VASP pathway, but this was not the primary mechanism of inhibition by DHEA-S.
• DHEA-S synergized with nitric oxide to inhibit platelet aggregation.

Conclusions:

• DHEA-S inhibits platelet activation by mild stimuli without abolishing platelet functionality.
• DHEA-S may contribute to maintaining circulating platelets in a resting state.
• The role of DHEA-S in platelet function may be particularly relevant when vascular endothelium function is impaired.