Maintenance of Erection of Penile Glans, but not Penile Body, after Transection of Rat Cavernous Nerves

Abstract

Two experiments tested the widely held assumption that the cavernous nerves (CN) are essential not only to erection of the penile body, via the corpora cavernosa, but also to erection of the glans penis, via the corpus spongiosum. In Experiment 1, the copulatory behavior and reflexive erections of male rats were studied before and after the CN were transected bilaterally (n = 8), unilaterally (n = 6), or sham-operated (n = 6). In postoperative tests, bilaterally operated males were severely impaired in their attempts to effect intromission, and they had the expected deficits in reflexive erections of the penile body, but their capacity for erection of the glans penis was only minimally impaired. Sham-operated males were unaffected by surgery, and unilaterally transected males had intermediate values. Experiment 2 tested the hypothesis that activity of the bulbospongiosus muscles was responsible for the residual erectile capacity of the glans after CN transection in Experiment 1. Males had bilateral sections of the CN (n = 9), or of the nerves innervating the bulbospongiosus muscles (n = 10), or of both of these nerves (n = 8), or sham surgery (n = 10). Relative to CN transection alone, the combined denervation further reduced glans penis erections, but did not eliminate them. These results suggest that the cavernous nerves of the rat are not the only peripheral nerves facilitating vascular engorgement of the corpus spongiosum.

Effect of sildenafil administration on penile hypoxia induced by cavernous neurotomy in the rat

“…14,[24][25][26][27][28] Loss of neural activity triggers a cascade of events-including hypoxiathat finally leads to damage to penile cell viability Effect of sildenafil administration on penile hypoxia L Vignozzi et al and tissue structure. [14][15][16] The rat BCN model has in one hand the advantage to mimic on human penile innervation the effect of radical retropubic prostatectomy, but in the other one it has the limitation to not isolate the different components that contribute to the penile damage and erectile dysfunction.…”

Multiple vasodilator pathways from the pelvic plexus to the penis of the rat

“…Moreover, denervation may not have an equal effect on all penile tissues. Sachs and Liu 30 found that transection of the MPN and all ®ne branches coursing toward the corpora cavernosa penis and urethra (presumably, the`®ne branches' correspond to lateral and ventral penile nerves) weakens, but does not prevent moderate to strong erection of the glans penis.…”

Spinal control of penile erection

“…Therefore, the two erectile tissues seem to be controlled by separate neural pathways. In the rat, persistence of glans erections following cavernous nerve section reinforces this hypothesis [136]. It has been reported that 75% and 80% of patients displaying lesions located at the conus terminatis or the cauda equina levels, respectively, can have reflexive erections [24].…”

“…Flips are elicited by corpus cavernosum erection and IC activity. Accordingly, reflexive erections represent a complex activation of automatic proerectile pathways to the corpus cavernosum and corpus spongiosum combined with somatic pathways to the IC and BS muscles [46,52,131,136]. Intracavernous pressure recordings during reflexive erections in the rat provide a physiological demonstration of the activation of autonomic and somatic neural pathways [8].…”