The molecular effects of electrical stimulation on the muscle components of the urethra of female rats after trauma by vaginal distention.

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.