Neonatal platelets support primary haemostasis and thrombin generation as well as
adult platelets, despite observable hypoaggregability in vitro. High prostaglandin E2 levels at accouchement could account for inhibited platelet function via the EP4
receptor. We set out to determine prostaglandin E2 plasma levels in cord blood of healthy neonates and evaluate the impact of prostaglandin
E2 on platelet function in adult and cord blood samples. Prostaglandin E2 plasma levels were measured in cord blood and venous adult blood using GC-MS. Impact
of prostaglandin E2 on platelet aggregation was measured by spiking cord blood and adult samples. Contributions
of EP3 and EP4 receptors were evaluated using respective antagonists. Intracellular cAMP concentrations
were measured using a commercial ELISA-kit. Prosta-glandin E2 plasma levels were substantially higher in cord blood than in adult samples. Spiking
with prostaglandin E2 resulted in a slight but consistent reduction of platelet aggregation in adult blood,
but response to PGE2 was blunted in cord blood samples. Aggregation response of spiked adult samples was
still higher than with non-spiked cord blood samples. Blockage of EP4 receptors resulted
in improved platelet aggregation in adult platelets upon prostaglandin E2 spiking, while aggregation in cord blood samples remained unaltered. Intracellular
cAMP concentrations after preincubation with prostaglandin E2 were only increased in adult samples. In conclusion, very high prosta -glandin E2 concentrations in cord blood affect platelet function. This effect may partially
explain neonatal platelet hypoaggregability. Peak levels of prostaglandin E2 can potentially protect against birth stressinduced platelet activation.
Keywords
Cyclic AMP - neonate - prostaglandin E
2
- prostanoid receptor EP4 - platelet aggregation