Penile Erection Induced by Stimulation of Sacral S1/S2 Spinal Root in Cats

This study aimed at determining whether stimulation of sacral spinal roots can induce penile erection in cats.

In anesthetized cats, a 20-gauge catheter was inserted into the corpus cavernosum to measure the penile pressure. Stimulus pulses (5-80 Hz, 0.2 ms) were applied through bipolar hook electrodes to sacral ventral roots alone or to combined ventral and dorsal roots of a single S1-S3 segment to induce penile pressure increases and penile erection.

Stimulation of the S1 or S2 ventral root at 30 to 40 Hz induced observable penile erection with rigidity and the largest increase (169 ± 11 cmH₂O) in penile pressure. Continuous stimulation (10 minutes) of afferent and efferent axons by simultaneous stimulation of the S1 or S2 dorsal and ventral roots at 30 Hz also produced a large increase (190 ± 8 cmH₂O) in penile pressure that was sustainable during the entire stimulation period. After a complete spinal cord transection at the T9-T10 level, simultaneous stimulation of the S1 or S2 dorsal and ventral roots induced large (186 ± 9 cmH₂O) and sustainable increases in penile pressure.

This study indicates the possibility to develop a novel neuromodulation device to restore penile erection after spinal cord injury using a minimally invasive surgical approach to insert a lead electrode through the sacral foramen to stimulate a sacral spinal root.