Neurourology and Urodynamics. 2019;1–10. wileyonlinelibrary.com/journal/nau © 2019 Wiley Periodicals, Inc. | 1 Received: 17 September 2019 | Accepted: 18 November 2019 DOI: 10.1002/nau.24243 ORIGINAL BASIC SCIENCE ARTICLE The molecular effects of electrical stimulation on the muscle components of the urethra of female rats after trauma by vaginal distention Gisela R. F. Salerno PhD 1 | Maria A. T. Bortolini MD, PhD 1 | Regina C. T. Gomes PhD 2 | Suellen M. Feitosa PhD 1 | Manuel J. Simões PhD 2 | Edmar Zanoteli MD, PhD 3 | Fernanda L. Castanho PhD 1 | Rodrigo A. Castro MD, PhD 1,4 1 Department of Gynecology, Sector of Urogynecology and Vaginal Surgery, Universidade Federal de São Paulo, São Paulo, Brazil 2 Histology and Structural Biology Division, Department of Morphology and Genetics, Universidade Federal de São Paulo, São Paulo, Brazil 3 Department of Neurology, Faculdade de Medicina da Universidade de São Paulo, Hospital das Clínicas, São Paulo, Brazil 4 Sector of Gynecology, Hospital Samaritano, São Paulo, Brazil Correspondence Maria Augusta Tezelli Bortolini, MD, PhD, Department of Gynecology, Sector of Urogynecology and Vaginal Surgery, Universidade Federal de São Paulo; Rua Botucatu, 740 ‐ Vila Clementino ‐ São Paulo 04023900, Brazil. Email: maria.augusta@gmail.com Abstract Aims: To evaluate the expression of genes and proteins related to the urethral muscles of female rats after trauma by vaginal distention (VD) and after electrical stimulation therapy (EST). Methods: We compared the urethras of four groups of 20 animals each: control without trauma (C), 7 (recent‐trauma) and 30 days (late‐trauma) post‐VD, and VD‐ treated with EST. We evaluated the expression of myogenic regulatory factors MYOD1 and myogenin (MYOG); skeletal muscle myosin heavy chain 1, 2, and 3 (MYH1, MYH2, and MYH3); smooth muscle MYH11; and myosin light chain 9 (MYL9). We used real‐time quantitative polymerase chain reaction, Western blot analysis, and immunohistochemistry. Results: MYOD1 and MYOG genes were overexpressed in the recent‐trauma group compared with the other groups (P < .05). MYH1 and MYH3 genes were upregulated in the recent‐trauma group compared with the control and EST groups (P < .05). The MYH2 gene was overexpressed in the late‐trauma group (P < .05), while the MYH2 protein was significantly increased in the EST group compared with control, recent‐trauma and late‐trauma groups by 5‐,3‐, and 2.7‐fold change, respectively (P < .05). MYL9 and MYH11 messenger RNA were overexpressed in both trauma groups compared with control and EST groups (P < .05). MYH11 protein was not different among the study groups (P > .05). Conclusions: EST enhances the recovery of the damaged urethral tissue of rats mainly by acting on the striated‐muscle components. The MYH2 pathway underlies the positive effects of EST in the external urethral sphincter. KEYWORDS electrical stimulation therapy, female rats, muscle, urethra, vaginal distension 1 | INTRODUCTION Stress urinary incontinence (SUI) is defined as the involuntary loss of urine upon effort or physical exertion. 1 The mechanism of urinary continence depends on the integrity and functionality of the pelvic floor and the urethra. SUI may reflect the impairment of the components of the urethral sphincteric mechanism. 2