This study aims to activate the external urethral sphincter (EUS), which plays a critical role in micturition control, through optogenetics and to determine its potential contribution to the stabilization of sensitized micturition activity. The viral vector (AAV2/8-CMV-hChR2(H134R)-EGFP) is utilized to introduce light-gated ion channels (hChR2/H134R) into the EUS of wild-type C57BL/6 mice. Following the induction of sensitized micturition activity using weak acetic acid (0.1%) in anesthetized mice, optical stimulation of the EUS muscle tissue expressing channel rhodopsin is performed using a 473 nm laser light delivered through optical fibers, and the resulting changes in muscle activation and micturition activity are examined. Through EMG (electromyography) measurements, it is confirmed that optical stimulation electrically activates the EUS muscle in mice. Analysis of micturition activity using cystometry reveals a 70.58% decrease in the micturition period and a 70.27% decrease in the voiding volume due to sensitized voiding. However, with optical stimulation, the micturition period recovers to 101.49%, and the voiding volume recovered to 100.22%. Stimulation of the EUS using optogenetics can alleviate sensitized micturition activity and holds potential for application in conjunction with other micturition control methods.
Keywords: continence; external urethral sphincter; micturition; optogenetics; striated muscle.