Prostaglandin E2 facilitates excitatory synaptic transmission in the nucleus tractus solitarii of rats.

Prostaglandin E2 (PGE2) binding sites are rich in the nucleus tractus solitarii (NTS). We studied the effects of PGE2 on evoked excitatory postsynaptic currents (eEPSCs) and miniature EPSCs (mEPSCs) in voltage-clamped neurons in rat NTS slices. eEPSCs and mEPSCs, mediated by non-NMDA glutamate receptors, fluctuated in size from event to event. In 37.5% of neurons, PGE2 increased the mean size of eEPSCs and changed the size distribution non-proportionally. In 42.9% of neurons, PGE2 increased the frequency of mEPSCs keeping the skewed size distribution unchanged. However, PGE2 did not modulate postsynaptic non-NMDA receptor sensitivity. We propose that size distributions of eEPSCs before and after PGE2 application are predictable from those of mEPSCs by quantal analysis with multinomial distribution. Our results suggest that PGE2 facilitates evoked and spontaneous release of glutamate vesicles.