Rhythmic motor patterns accompanying ejaculation in spinal cord-transected male rats.

A spinal pattern generator controls the ejaculatory response. Activation of this spinal generator elicits rhythmic motor patterns of the striated musculature that surrounds the genital tract that contributes to the expulsion of seminal secretions. In the present study, we elicited ejaculation in spinal cord-transected male rats by mechanically stimulating the urethra and registered rhythmic motor patterns in the cremasteric, iliopsoas and pubococcygeus muscles. The rhythmic motor activity recorded in these muscles was compared with that elicited in the bulbospongiosus muscles; the results revealed similarities in the motor parameters among all the muscles. Data of this study, showing the occurrence of rhythmic motor behaviour in the cremasteric, iliopsoas and pubococcygeus muscles during ejaculation, suggest that these muscles might be under the control of the spinal generator for ejaculation.