Neurosteroids enhance bandpass filter characteristics of the rat Schaffer collateral-to-CA1 synapse

Neurosteroids are important modulators of synaptic activity in the mammalian central nervous system. We have shown previously that the neurosteroid, pregnenolone sulfate (PREGS) enhances paired-pulse facilitation at the Schaffer collateral-to-CA1 synapse in rat hippocampal slices. Here we show that PREGS enhances the facilitation of postsynaptic potentials (PSPs) during a 300 ms train of repetitive stimuli at frequencies between 10 and 50 Hz. At higher or lower frequencies, however, PREGS does not affect the PSPs produced by repetitive stimuli. This enhancement of the bandpass filtering characteristic of a central synapse by a naturally occurring neurosteroid could selectively influence transmission at bursting or other highly active synapses.