Aspirin changes short term synaptic plasticity in CA1 area of the rat hippocampus

Introduction: The prostaglandin E2 (PGE2), a cyclooxygenase (COX) product, play critical roles in the synaptic plasticity. Therefore, long term use of COX inhibitors may impair the synaptic plasticity. Considering the wide clinical administration of aspirin and its unknown effects on information processing in the brain, the effect of aspirin and sodium salicylate on the short term synaptic plasticity was investigated. Methods: Field excitatory post synaptic potential (fEPSP) from stratum radiatum of CA1 neurons were recorded following Schaffer collateral stimulation in rats receiving aspirin in drinking water (2 mg/ml) for 6 weeks or sodium salicylate (six injection of 300 mg/kg, IP, twice daily) for 3 days. In order to examine the short-term synaptic plasticity, paired pulse stimulations with inter pulse intervals (IPI) of 20, 80, and 200 ms were applied and paired pulse index (PPI) was calculated. Results: The data showed that both sodium salicylate and aspirin decreased basal synaptic responses, although this change was significant in the sodium salicylate group, but not in aspirin treated rats (ANOVA; P<0.001). Sodium salicylate significantly increased PPI at 20 ms IPI (% 90.7 +/- 1.6, n=5Vs. control: % 76.1 +/- 1.5, n=5). Also significant increase in PPI was observed in aspirin treated rats (% 125.9 +/- 6.6, n=5) at 20 ms IPI compared to control ones (% 76.3 +/- 2.4, n=5, P<0.05, unpaired t-test). Conclusion: In summary, our study suggests that aspirin and sodium salicylate may affect synaptic transmission and short term synaptic plasticity in the rat hippocampus.