Imbalance between matrix metalloproteinase-1 (MMP-1) and tissue inhibitor of metalloproteinase-1 (TIMP-1) contributes to bladder compliance changes in rabbits with partial bladder outlet obstruction (PBOO)

Objective To investigate the underlying mechanisms of bladder compliance after partial bladder outlet obstruction (PBOO) and the role of the collagen degradation enzyme matrix metalloproteinase-1 (MMP-1) and its endogenous inhibitor tissue inhibitor of metalloproteinase-1 (TIMP-1) during this process. Materials and Methods Bladder compliance of control, sham-operated and PBOO rabbits was measured using a UDS-600 urodynamic testing machine. Collagen deposition between and within the detrusor smooth muscle bundles was evaluated using Masson's Trichrome stain and transmission electron microscopy. The expression levels of MMP-1 and TIMP-1 were evaluated by Western blot. Results Bladder compliance decreased after PBOO. Collagen deposition increased both between and within the detrusor smooth muscle bundles, and had an inverse relationship with bladder compliance. MMP-1 and TIMP-1 expression negatively correlated with bladder compliance. Conclusion These findings indicate that the imbalance between MMP-1 and TIMP-1 favours accumulation of extracellular collagen, the structural components associated with decreased bladder compliance after PBOO.