Maintenance of erection of penile glans, but not penile body, after transection of rat cavernous nerves.

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.