The purpose of the present study was to determine the contribution of the external urethral sphincter (EUS), the ischiocavernous (IC), or the bulbospongiosus (BS) on the control of micturition, copulatory behavior and semen expulsion in male rats. We hypothesized that the EUS contributes to maintain urinary continence, while all three muscles participate in expulsive urethral functions.
In Experiment 1, it was analyzed the effects of bilateral denervation of IC, BS or EUS, or sham surgery, on voiding behavior and urinary parameters measured before surgery and 2 and 10 days post-surgery. In Experiment 2, copulatory behavior and the weight of the seminal plug expelled during ejaculation were recorded before and after sham surgery or bilateral denervation of the aforementioned muscles. Immediately after ejaculation, the animals were anesthetized to confirm the denervation and determine whether seminal material had accumulated in the lower urinary tract.
In IC-denervated animals, voiding duration and the number of mounts was increased, and intromission or ejaculation patterns were absent. Denervation of BS induced signs of post-micturition dribble, decreased voiding frequency, increased urine volume and reduced the amount of semen ejaculated. Denervation of EUS induced signs of post-micturition dribble and urinary incontinence, as well as retrograde ejaculation.
Striated muscles anatomically related to the urethra contribute differentially to the control of continence and expulsive urethral functions. Damages to the muscles or to their innervation, as may occur during pelvic surgery, would result in sexual and urinary dysfunctions. Neurourol. Urodynam. 33:437–442, 2014. © 2013 Wiley Periodicals, Inc.