Abstract
Purpose: Underactive bladder (UAB) is a challenging urological condition lacking effective pharmacological treatments. While silk sericin has demonstrated anti-apoptotic properties in other tissues, its application in bladder dysfunction remains unexplored. This study investigated the effect of silk sericin on apoptotic markers and urodynamic outcomes in a lumbar canal stenosis (LCS)-induced rat model of UAB, with the novelty centered on evaluating sericin's therapeutic potential specifically in bladder tissue. Methods: Thirty-six female Wistar rats were randomized into six groups: control, sham, UAB model (LCS+normal saline), and LCS+sericin (200, 250, or 300 mg/kg/day, orally for 14 days). UAB was induced via LCS by insertion of silicone rubber at L5–L6. Bladder function was assessed by awake urodynamics, bladder weight, and Western blotting of apoptotic proteins (Bax, Bcl-2, caspase-3, caspase-9). Outcome assessments were performed blinded to treatment group. Representative urodynamic tracings were obtained for each group. Results: Urodynamic evaluation showed significant improvement limited to the intercontraction interval (ICI), which significantly improved with sericin 300 mg compared with LCS (p=0.041). No significant improvements were observed in other urodynamic parameters, including peak pressure, contraction amplitude, or contraction frequency. Bladder weight was significantly increased in LCS rats (indicating possible hypertrophy or edema) and was significantly reduced in the sericin 300 mg group versus LCS (p=0.004). Apoptotic markers Bax and cleaved caspase-3/procaspase-3 decreased significantly with sericin, whereas Bcl-2 expression increased. The most pronounced effects were observed at 300 mg/kg. Conclusion: Sericin demonstrated anti-apoptotic and partial functional protective effects (limited to ICI) in the LCS-induced UAB model, particularly at 300 mg/kg. However, dissociation between apoptotic modulation and functional recovery indicates that anti-apoptotic mechanisms alone may be insufficient to restore detrusor contractility. These preliminary findings suggest sericin as a candidate requiring further investigation, though extensive mechanistic, pharmacokinetic, and long-term studies with histological validation are warranted before translational consideration.