In vivo firing behavior of lumbosacral parasympathetic preganglionic nucleus neurons in the spinal cord during micturition.

This is the authors' abstract. We don't add key points for this paper.

The sacral spinal parasympathetic preganglionic nucleus (PPN) has an important role in the micturition reflex. However, it is not fully understood how the PPN neurons behave as efferents to control bladder activity. We developed an in vivo recording technique to identify “bladder-responsive” neurons in the lumbosacral PPN whose firing pattern dynamically tracks increases in intravesical pressure (IVP). These bladder-responsive lumbosacral PPN neurons are basically silent during the storage phase, but start to show graded ramping increases in firing as IVP increases, and show a stronger increase in firing during voiding contractions. Bladder-responsive lumbosacral PPN neurons also show synchronized bursting with subthreshold IVP increases (non-voiding contractions). Although voiding required a substantially higher firing frequency (> 10 Hz) than that observed during non-voiding contractions, the amplitude of peak IVP during voiding did not correlate with the maximum PPN firing frequency. Lumbosacral PPN neurons may precisely control bladder contractions to induce micturition.