Copulatory behavior and reflexive penile erection in rats after section of the pudendal and genitofemoral nerves

Two experiments probed the roles of the pudendal and genitofemoral nerves in sexual behavior. Male rats were tested for copulatory behavior and reflexive erections after transection of the sensory (SP) or motor (MP) branches of the pudendal nerves and, in Experiment 2, section of the genitofemoral (GF) nerve alone or in combination with the SP nerves. Damage to the GF nerve had no apparent effects. Division of the SP nerve severely impaired the ability of males to achieve intromission, and hence ejaculation, and reflexive erections were drastically reduced. However, this treatment caused impairments less complete than those previously described for more distal deafferentation by section of the dorsal penile nerves or by application of topical anesthetics to the glans penis. Penile autotomy following SP section was delayed but not avoided by daily treatment with amitriptyline. Transection of the MP nerves had the most drastic effects, preventing reflexive erections, although some intromissions (but no ejaculations) occurred during copulation. Although urinary function was also disrupted by MP transection, the impairment in sexual function is tentatively ascribed to chronic hyperinvolution of the penile corpora following loss of phasic vasoconstrictive stimulation normally supplied via the MP nerves. The pattern of results suggests that the pudendal nerves make different contributions to penile erection in different contexts.