Aspirin-Dependent Effects on Purinergic P2Y1 Receptor Expression

Area of Science:

• Pharmacology
• Hematology
• Molecular Biology

Background:

• Chronic aspirin treatment in healthy volunteers leads to recovery of adenosine diphosphate (ADP)-induced platelet activation.
• The purinergic P2Y1 receptor, which signals through a Gq-protein, shares a pathway with the thromboxane-A2 receptor.
• Aspirin's effect on platelet activation recovery is not fully understood, particularly the underlying molecular mechanisms.

Purpose of the Study:

• To investigate the hypothesis that chronic aspirin exposure increases P2Y1 receptor expression, contributing to the recovery of ADP-induced platelet activation.
• To elucidate the role of the peroxisome proliferator-activated receptor alpha (PPARα) in aspirin-induced P2Y1 receptor regulation.
• To explore whether platelet adaptation to aspirin involves receptor-specific or pathway-specific mechanisms.

Main Methods:

• In vitro studies using human megakaryoblastic DAMI cells and human megakaryocytic progenitor cell cultures treated with aspirin or WY14643 (PPARα agonist).
• In vivo experiments involving platelets from healthy volunteers treated with aspirin for 8 weeks.
• Analysis of platelets from patients undergoing chronic aspirin therapy for varying durations (less than one month vs. more than two months).

Main Results:

• Aspirin and WY14643 significantly up-regulated P2Y1 mRNA expression in DAMI cells and megakaryocytic progenitors in a PPARα-dependent manner.
• Platelets from healthy volunteers on chronic aspirin treatment showed increased P2Y1 expression.
• Patients on long-term aspirin therapy exhibited higher P2Y1 expression and enhanced ADP-induced aggregation compared to those on short-term therapy.

Conclusions:

• Aspirin induces genomic changes in megakaryocytes, leading to the up-regulation of P2Y1 receptor expression.
• The nuclear receptor PPARα is involved in mediating aspirin's effect on P2Y1 receptor regulation.
• Platelet adaptation to pharmacological inhibition may involve multiple receptors sharing the same Gq-protein signaling pathway, rather than being receptor-specific.