The Antimuscarinic Agent Tolterodine Regulates Bladder Extracellular Matrix in Partial Bladder Outlet Obstruction in Rats

Abstract

Background/Aims: Antimuscarinic agents can delay the progression of bladder dysfunction caused by bladder outlet obstruction (BOO). To date, the relationship between muscarinic receptor activity and the bladder extracellular matrix (ECM) remains unclear. Thus, an animal model of partial BOO (PBOO) in female rats was established to explore the variation in bladder wall ECM proteins under PBOO conditions with antimuscarinic agent administration. Methods: Rats were randomly divided into three groups: sham, PBOO, and PBOO plus tolterodine. Picrosirius red staining was used to examine the smooth muscle and collagen content of bladder samples. Gene microarray and RT-PCR were performed to survey the expression of ECM proteins, receptors, and metabolism regulators in the rat bladder. Positive results were further evaluated by immunohistochemistry. Results: Picrosirius red staining showed that smooth muscle volume significantly increased in the PBOO and PBOO plus tolterodine groups (p < 0.05), while collagen significantly increased in the PBOO group (p < 0.05) but not in the PBOO plus tolterodine group. Gene microarray and RT-PCR revealed that none of the collagen subtypes exhibited significant changes after PBOO establishment and tolterodine administration. However, matrix metalloproteinases (MMPs) increased significantly in the PBOO plus tolterodine group (p < 0.05). Additionally, PBOO inhibited the expression of non-collagen ECM proteins in the rat bladder wall, while tolterodine induced the expression of non-collagen ECM proteins and ECM receptors. Conclusions: Tolterodine decreased the volume of collagen in PBOO rat bladder wall, possibly via MMPs, and regulated the expression of ECM proteins and receptors.