DIRECT NITRIC OXIDE-CONTAINING INNERVATION FROM THE RAT SPINAL-CORD TO THE PENIS

Nitric oxide synthase (NOS) -immunoreactive pathways to the rat penis were studied by combining retrograde tracing by Fluorogold with NOS im munohistochemistry. Injection of the tracer into the penile shaft resu lted in Fluorogold labelling in a vast number of NOS-immunoreactive ne urons in the major pelvic ganglion. In addition, some neurons in the s pinal cord intermediolateral column consistently contained Fluorogold label in the upper lumbar levels. Most of these neurons were also NOS- immunoreactive. These findings suggest that the sympathetic preganglio nic, NOS-containing neurons project to the penis, and they may partici pate in nitric oxide-mediated penile erection.