Margarita Juárez

Neuroanatomic and behavioral correlates of urinary dysfunction induced by vaginal distension in rats

The aim of the present study was to use a model of simulated human childbirth in rats to determine the damage to genitourinary structures and behavioral signs of urinary dysfunction induced by vaginal distension (VD) in female rats. In experiment 1, the length of the genitourinary tract and the nerves associated with it were measured immediately after simulated human delivery induced by VD or sham (SH) procedures. Electroneurograms of the dorsal nerve of the clitoris (DNC) were also recorded. In experiment 2, histological characteristics of the bladder and major pelvic ganglion of VD and SH rats were evaluated. In experiment 3, urinary parameters were determined in conscious animals during 6 h of dark and 6 h of light before and 3 days after VD or SH procedures. VD significantly increased distal vagina width (P < 0.001) and the length of the motor branch of the sacral plexus (P < 0.05), DNC (P < 0.05), and vesical nerves (P < 0.01) and decreased DNC frequency and amplitude of firing. VD occluded the pelvic urethra, inducing urinary retention, hematomas in the bladder, and thinness of the epithelial (P < 0.05) and detrusor (P < 0.01) layers of the bladder. Major pelvic ganglion parameters were not modified after VD. Rats dripped urine in unusual places to void, without the stereotyped behavior of micturition after VD. The neuroanatomic injuries after VD occur alongside behavioral signs of urinary incontinence as determined by a new behavioral tool for assessing micturition in conscious animals.

Genitourinary dysfunction in male rats after bilateral neurectomy of the motor branch of the sacral plexus

To determine the contribution of the striated musculature anatomically related to the urethra on urinary continence in conscious male rats. We tested whether the bilateral neurectomy of the motor branch of the sacral plexus (MBSP), a nerve that innervates the bulbospongiosus, ischiocavernosus, and external urethral sphincter, is a reliable procedure to induce changes in voiding pattern that can be used as indicators of urinary incontinence in unanesthetized male rats.

MP38-20 TRANSCUTANEOUS ELECTRICAL STIMULATION OF DORSAL NERVE OF CLITORIS FACILITATES URINARY CONTINENCE RECOVERY AFTER VAGINAL DISTENSION IN RATS

INTRODUCTION AND OBJECTIVES: Vaginal distension (VD) injures the external urethral sphincter, stretches pelvic nerves and induces urine leakage, a behavioral sign of stress urinary incontinence. Electrical pudendal nerve stimulation accelerates recovery from urinary incontinence. The aim of the present study was to determine whether in conscious rats transcutaneous electrical stimulation (TES) of the DNC facilitates urinary continence recovery after VD. METHODS: Twenty adult nulliparous Wistar female rats (250e300 g) were anesthetized (ketamine, 60 mg/kg and xylazine, 7.5 mg/kg, ip) to undergo 4 h of VD (n1⁄48), shamVD (n1⁄45) or VD+TES (n1⁄47). In VD animals, a 10-F Foley balloon catheter was inserted into the vagina and filledwith 4ml of water for 4 h. In SHanimals, the catheter was placed into the vagina but not inflated. In the VD+TES animals, 3 stimulations (immediately, and 2 and 5 days after VD) were applied to the clitoral sheath for one hour with a pair of electrodes (0.9 mA, 20 Hz and 0.2ms of duration). Micturition behavior and urinary parameters were evaluated during 6 h of dark, before and at 1, 3, 6 and 8 days after VD or SH VD. RESULTS: Before VD, rats show a stereotyped behavior of micturition. No rat leaked urine. Voiding frequency and voiding volume were, 10+0.7 voids and 0.59+0.2 ml, respectively. After VD, stereotyped voiding behavior decreased at 1 day. From 1 to 3 days post VD, 100% of VD rats, with and without TES, leakage urine during behaviors implicating stress such as standing to reach food, sneezing, scratching, or standing on their hind legs for vertical exploration. Six and 8 days after VD, the percent of animals dripping urine decreased with TES (day 6, 70%; day 8, 28%) compared to those without TES (day 6, 87%; day 8, 75%). A similar effect of TES was observed on the number of leaks per animal at day 8 (TES 6 3 vs without TES 29 7; p<0.001). CONCLUSIONS: VD-induced behavioral signs of urinary incontinence decrease gradually after the first 5 days post VD and TES accelerates functional recovery of continence. Further studies are required to compare effectivity of TES vs direct electrical pudendal nerve stimulation (invasive technique) on nerve regeneration after VD.