Upregulation of heme oxygenase and collagen type III in the rat bladder after partial bladder outlet obstruction

β-Adrenoceptor Signaling Activation Improves Bladder Fibrosis by Inhibiting Extracellular Matrix Deposition of Bladder Outlet Obstruction

BACKGROUND

Partial bladder outlet obstruction (pBOO) causes deposition of extracellular matrix (ECM), promotes bladder fibrosis, and decreases bladder compliance.

METHODS

To investigate the effect of β-adrenoceptor (ADRB) on the ECM deposition of pBOO rat model and explore its underlying mechanism, human bladder smooth muscle cells (hBSMCs) were exposed to the pathological hydrostatic pressure (100 cm H2O) for 6 h, reverse transcription-polymerase chain reaction (RT-PCR) and western blotting were employed. Then the rats of sham operation and pBOO model were treated with vehicle or ADRB agonists for 3 weeks, and the alterations of the bladder were observed via Masson staining and immunohistochemical analysis.

RESULTS

100 cm H2O hydrostatic pressure significantly upregulated the expression of collagen I (COL1), collagen III (COL3) and fibronectin (FN), and downregulated the expression of ADRB2 and ADRB3 of hBSMCs at 6 h. The agonists of ADRB2 and ADRB3, Formoterol and BRL 37344, decreased COL1 and FN expression of hBSMCs under 100 cm H2O for 6 h compared with the cells exposed to hydrostatic pressure only. As the classic downstream pathways of ADRB, the EPAC pathway inhibited COL1 and FN expression of hBSMCs via regulating SMAD3 and SMAD2 activities, respectively. In pBOO rats, Procaterol (ADRB2 agonist), and Mirabegron (ADRB3 agonist) inhibited the formation of collagen and decreased the expression of FN and COL1 in the bladders of pBOO rats.

CONCLUSIONS

The bladder fibrosis of pBOO and deposition of hBSMCs ECM under hydrostatic pressure were regulated by ADRB2, and ADRB3 via EPAC/SMAD2/FN and EPAC/SMAD3/COL1 pathways, these findings pave an avenue for effective treatment of pBOO.

Partial recovery of voiding function in female mice following repeated psychological stress exposure

Psychological stress causes bladder dysfunction in humans and in rodent models, with increased urinary frequency and altered contractile responses evident following repeated environmental stress exposure. However, whether these changes persist after removal of the stressor is unknown, and the aim of this study was to determine if stress-induced changes in voiding behaviour and bladder function recover following removal of the stressor. Adult female mice were allocated to three groups: Unstressed, Stressed or Stressed + Recovery. Animals in the stressed groups were exposed to water avoidance stress for 1h/day for 10-days, with unstressed animals age-matched and housed under normal conditions. For recovery studies, animals were housed without stress exposure for an additional 10-days. Voiding behaviour was assessed periodically and animals sacrificed on day 10 (Unstressed and Stressed) or day 20 (Unstressed and Stressed + Recovery). Isolated whole bladder studies were used to assess compliance, urothelial mediator release and contractile responses. Exposure to stress increased plasma corticosterone levels almost three-fold (P<0.05) but this returned to baseline during the recovery period. Contractile responses of the bladder to carbachol and KCl were also increased following stress, and again fully recovered after a 10-day stress-free period. In contrast, stress increased urinary frequency four-fold (P<0.001), but this did not return fully to baseline during the recovery period. Bladder compliance was unchanged by stress; however, it was increased in the stressed + recovery group (P<0.05). Thus, following a stress-free period there is partial recovery of voiding behaviour, with an increase in bladder compliance possibly contributing to the compensatory mechanisms.

Experimental long-term diabetes mellitus alters the transcriptome and biomechanical properties of the rat urinary bladder

Diabetes mellitus (DM) is the leading cause of chronic kidney disease and diabetic nephropathy is widely studied. In contrast, the pathobiology of diabetic urinary bladder disease is less understood despite dysfunctional voiding being common in DM. We hypothesised that diabetic cystopathy has a characteristic molecular signature. We therefore studied bladders of hyperglycaemic and polyuric rats with streptozotocin (STZ)-induced DM. Sixteen weeks after induction of DM, as assessed by RNA arrays, wide-ranging changes of gene expression occurred in DM bladders over and above those induced in bladders of non-hyperglycaemic rats with sucrose-induced polyuria. The altered transcripts included those coding for extracellular matrix regulators and neural molecules. Changes in key genes deregulated in DM rat bladders were also detected in db/db mouse bladders. In DM rat bladders there was reduced birefringent collagen between detrusor muscle bundles, and atomic force microscopy showed a significant reduction in tissue stiffness; neither change was found in bladders of sucrose-treated rats. Thus, altered extracellular matrix with reduced tissue rigidity may contribute to voiding dysfunction in people with long-term DM. These results serve as an informative stepping stone towards understanding the complex pathobiology of diabetic cystopathy.

Effect of stress on the expression of rho-kinase and collagen in rat bladder tissue

PURPOSE

We examined the effect of stress on the pathophysiology of bladder stability in terms of enzyme levels, Rho-kinase, and bladder relaxation.

MATERIALS AND METHODS

A total of 48 female Sprague-Dawley rats were studied in scheduled stress environments for 7, 14, and 28 days; 24 rats were in the control group and 24 rats were in the test (stressed) group.

RESULTS

Estrogen decreased significantly whereas testosterone and dopamine increased significantly in the stress group (p<0.05). Rho-kinase was significantly increased in the rats exposed to stress stimuli for 14 days (p<0.05). Collagen types I and III in the bladder tissue were significantly higher in rats exposed to stress for 14 days and 28 days (collagen type I in the 14-day group, p<0.01; collagen type I in the 28-day group, p<0.05; collagen type III in the 14-day and 28-day groups, p<0.05). Voiding frequency increased significantly as the duration of stress exposure was prolonged, in addition to a significant decrease in volume per voiding (p<0.05).

CONCLUSIONS

The changes observed in micturition pattern, factors that contribute to smooth muscle contraction, and relaxation in the female rat bladder support the hypothesis that stress affects bladder stability.

The bladder extracellular matrix. Part I: architecture, development and disease

From the earliest studies with epithelial cells implanted into detrusor muscle to later experiments on smooth muscle in defined collagen gels, cell niche and extracellular matrix (ECM) have been clearly shown to orchestrate cellular behavior and fate whether quiescent, migratory, or proliferative. Normal matrix can revert transformed cells to quiescence, and damaged matrix can trigger malignancy or dedifferentiation. ECM influence in disease, development, healing and regeneration has been demonstrated in many other fields of study, but a thorough examination of the roles of ECM in bladder cell activity has not yet been undertaken. Structural ECM proteins, in concert with adhesive proteins, provide crucial structural support to the bladder. Both structural and nonstructural components of the bladder have major effects on smooth muscle function, through effects on matrix rigidity and signaling through ECM receptors. While many ECM components and receptors identified in the bladder have specific known functions in the vascular smooth musculature, their function in the bladder is often less well defined. In cancer and obstructive disease, the ECM has a critical role in pathogenesis. The challenge in these settings will be to find therapies that prevent hyperproliferation and encourage proper differentiation, through an understanding of matrix effects on cell biology and susceptibility to therapeutics.