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

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 VDtreated 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.

Electrotherapy for urethral modulation: Are extracellular matrix molecules and growth factors potential targets?

“…The authors evidenced that electrotherapy acts through the molecular pathway of skeletal muscle myosin heavy chain expression since MYH2 levels were higher in rats that received electric current than in the injured and untreated group. 14 Following the same research line, our current results suggest that electrotherapy does not directly interfere with VEGF, NGF, COL3a1, and LOXL1 molecules in the long term, since we observed no changes in their expression due to treatment at the level of mRNA and proteins. However, it seems there is remodeling in the urethral tissue visually observed in the qualitative histological analysis, represented by an increase in the deposition of connective tissue and a small amount of blood vessels in the trauma group in relation to the other groups.…”

“…16 We applied electrotherapy treatment soon after VD trauma and continued it for 30 days to evaluate the effects of long-term treatment (i.e., a period corresponding to the tissue maturation and remodeling phase), comparing it to chronically injured urethras that have suffered the effects of the acute posttrauma process and spontaneous tissue regeneration. Salerno et al 14 observed that electrotherapy contributed to the structural regeneration of the urethra of rats injured by prolonged VD, mainly through the improved recovery of the skeletal muscles of the external sphincter of the urethra. The authors evidenced that electrotherapy acts through the molecular pathway of skeletal muscle myosin heavy chain expression since MYH2 levels were higher in rats that received electric current than in the injured and untreated group.…”

“…The general protocol of electrotherapy was first described by Franco et al 17 The animals were treated on the third day after trauma as experimental and clinical data suggest that the earlier we applied the electric current, the greater the chances of complete tissue repair and clinical benefits. 13,14 We used biphasic rectangular pulses at a low frequency generated by Tonustin DS702 device (VIOTTI) with a transvaginal probe of 2 mm diameter at a frequency of 50 Hz and a pulse width of 0.5 ms, and the intensity of the variable current ranged from 4 to 32 mA (TON/TOFF: 1: 1, 8 s each phase of 15 min). 17 This group received 12 sessions of 15 min/each three times a week for 30 days.…”

“…9,10 Moreover, the electric current increased the secretion of nerve growth factor (NGF), a marker of neural repair, 11 in cultures of mouse astrocyte cells and rat sciatic nerve Schwann cells, which suggests its potential for neural regeneration. 12,13 Recently, Salerno et al 14 reported the positive longterm effects of electrotherapy on the recovery of the EUS of female rats after trauma by prolonged VD. The authors observed increased expression of skeletal muscle myosin heavy chain IIa (MYH2) protein, as well as the structural reorganization of urethral muscle layers after treatment with electrotherapy.…”

“…The authors observed increased expression of skeletal muscle myosin heavy chain IIa (MYH2) protein, as well as the structural reorganization of urethral muscle layers after treatment with electrotherapy. 14 Muscle fiber may respond directly to electric current by the contraction of actin and myosin filaments, while ECM components may respond indirectly by regulating protein synthesis. 15 However, the molecular mechanisms of action of electrotherapy in the urethra towards its regeneration are not fully understood.…”