Alpha1A-adrenoceptor antagonist improves underactive bladder associated with diabetic cystopathy via bladder blood flow in rats

Therapeutic effects of silodosin and urapidil on underactive bladder associated with diabetic cystopathy

OBJECTIVES

Pharmacological treatment options for underactive bladder (UAB) syndrome are limited. Urapidil is the only alpha₁ -adrenoceptor (AR) antagonist that can be used for urinary disorders in women in some countries. However, no studies have directly verified the effects of alpha₁ -AR antagonists on the female urethra and UAB-like dysfunctions. We investigated the effects of silodosin (alpha_1A -AR antagonist) and urapidil (nonselective alpha₁ -AR antagonist) on the voiding function in female rats with diabetes mellitus (DM).

METHODS

Changes in intraurethral pressure (IUP) induced by midodrine (alpha₁ -AR agonist) and mean blood pressure (MBP) were continuously measured in normal female rats to verify the pharmacological profiles of the drugs. To establish a DM model, rats were administered streptozotocin (STZ; 50 mg/kg, intravenous). Eight weeks after STZ administration, drugs were subcutaneously delivered through an osmotic pump. Four weeks after drug administration, emptied bladder blood flow (BBF), intravesical pressure, and the micturition volume were measured.

RESULTS

Both silodosin and urapidil inhibited the midodrine-induced increase in IUP and decreased MBP in a dose-dependent manner. Silodosin had a more substantial effect on the lower urinary tract than on MBP. Twelve weeks after STZ administration, DM rats exhibited UAB-like dysfunction (increased bladder capacity/bladder weight and residual volume and decreased bladder voided efficiency) and decreased BBF. Both drug treatments controlled this dysfunction.

CONCLUSIONS

Alpha₁ -AR antagonists induced dose-dependent urethral relaxation in female rats. These drugs ameliorated UAB-like dysfunction in STZ-induced DM rats. In addition, alpha_1A -AR antagonists such as silodosin, which have limited effects on blood pressure, appear to be useful for treating UAB.

Established and emerging treatments for diabetes-associated lower urinary tract dysfunction

Dysfunction of the lower urinary tract (LUT) including urinary bladder and urethra (and prostate in men) is one of the most frequent complications of diabetes and can manifest as overactive bladder, underactive bladder, urinary incontinence, and as aggravated symptoms of benign prostate hyperplasia. We have performed a selective literature search to review existing evidence on efficacy of classic medications for the treatment of LUT dysfunction in diabetic patients and animals, i.e., α1-adrenoceptor and muscarinic receptor antagonists, β3-adrenoceptor agonists, and phosphodiesterase type 5 inhibitors. Generally, these agents appear to have comparable efficacy in patients and/or animals with and without diabetes. We also review effects of antidiabetic medications on LUT function. Such studies have largely been performed in animal models. In the streptozotocin-induced models of type 1 diabetes, insulin can prevent and reverse alterations of morphology, function, and gene expression patterns in bladder and prostate. Typical medications for the treatment of type 2 diabetes have been studied less often, and the reported findings are not yet sufficient to derive robust conclusions. Thereafter, we review animal studies with emerging medications perhaps targeting diabetes-associated LUT dysfunction. Data with myoinositol, daidzein, and with compounds that target oxidative stress, inflammation, Rac1, nerve growth factor, angiotensin II receptor, serotonin receptor, adenosine receptor, and soluble guanylyl cyclase are not conclusive yet, but some hold promise as potential treatments. Finally, we review nonpharmacological interventions in diabetic bladder dysfunction. These approaches are relatively new and give promising results in preclinical studies. In conclusion, the insulin data in rodent models of type 1 diabetes suggest that diabetes-associated LUT function can be mostly or partially reversed. However, we propose that considerable additional experimental and clinical studies are needed to target diabetes itself or pathophysiological changes induced by chronic hyperglycemia for the treatment of diabetic uropathy.

Effects of tadalafil versus silodosin on voiding function in male patients with non-neurogenic detrusor underactivity: A comparative study using propensity score matching

OBJECTIVES

To investigate and compare the effects of tadalafil and silodosin on lower urinary tract symptoms and voiding functions in men with non-neurogenic detrusor underactivity.

METHODS

A total of 126 treatment-naive men with lower urinary tract symptoms diagnosed as non-neurogenic detrusor underactivity received tadalafil (5 mg/day) or silodosin (8 mg/day) for 12 months. After propensity score matching, parameter changes from before administration to 12 months since treatment initiation were assessed based on subjective symptoms and urodynamic findings, including bladder contractility index and maximum urinary flow rate, and were compared between the tadalafil treatment group and the silodosin group. Detrusor underactivity was defined as bladder contractility index <100 and bladder outlet obstruction index <40.

RESULTS

After propensity score matching, the final analysis included 48 patients each in the tadalafil and silodosin groups. No significant differences in prostate volume, subjective symptoms or urodynamic parameters were detected between the groups at baseline. Compared with baseline, significant improvements in subjective symptoms and storage and voiding functions were observed at month 12 in both groups. Maximum urinary flow rate significantly improved by 1.7 mL/s in the silodosin group and by 3.0 mL/s in the tadalafil group. In addition, the mean bladder contractility index increased from 80.0 to 86.1 in the silodosin group and from 77.9 to 97.6 in the tadalafil group. Improvements in maximum urinary flow rate and bladder contractility index were significantly superior in the tadalafil group.

CONCLUSIONS

Both tadalafil and silodosin significantly improve lower urinary tract symptoms and voiding function in patients with non-neurogenic detrusor underactivity. Furthermore, tadalafil is more effective than silodosin in improving bladder contractility index and maximum urinary flow rate.

Pathogenesis evidence from human and animal models of detrusor underactivity

Detrusor underactivity (DU) is a common urodynamic diagnosis in patients with lower urinary tract symptoms and large post-voiding residual volume. Animal and human studies showed the possible etiologies of DU include central or peripheral nerve injury, bladder outlet obstruction, chronic ischemia, aging, diabetes mellitus, and sympathetic inhibition of micturition reflex. Evidence from animal and human DU studies with various etiologies revealed highly similar gross and histological characteristics in the bladders, including increased bladder weight, bladder wall thickening, inflammation, collagen deposition, and fibrosis. In electron microscopy, smooth muscle destruction, swollen mitochondria, decreased nerve innervation, caveolae, and umbrella cell fusiform vesicles were noted in the DU bladders. Most animal DU models demonstrate detrusor contractility changes from compensatory to the decompensatory stage, and the change was compatible with human DU observation. The cystometry in the DU animal studies is characterized by impaired contractility, prolong intercontraction interval, and hyposensation, while in vitro bladder muscle strips experiment may exhibit normal detrusor contractility. Decreased bladder blood flow and increased oxidative stress in bladders had been proved in different animal DU models, suggesting they should be important in the DU pathogenesis pathway. Sensory receptors mRNA and protein expression changes in DU bladders had been observed in both animal and human studies, including muscarinic receptors M2, M3, adrenergic receptor β3, purinergic receptor P2X1, P2X3, and transient receptor potential vanilloid (TRPV) 1 and TRPV4. Although some of the sensory receptors changes remain controversial, it might be the target for further pharmacologic treatments.

Therapeutic effect of integrin-linked kinase gene-modified bone marrow-derived mesenchymal stem cells for streptozotocin-induced diabetic cystopathy in a rat model

Background

Diabetic cystopathy (DCP) is a chronic complication of diabetes mainly within the submucosal and muscular layers of the bladder due to the hyperglycemia-induced ischemia. As no effective therapies are currently available, the administration of optimized mesenchymal stem cells (MSCs) provides a potential treatment of DCP. Thus far, new strategy, such as genetic modification of MSCs, has been developed and has shown promising outcomes of various disorders.

Methods

This study was conducted using integrin-linked kinase (ILK) gene-modified bone marrow-derived stem cells (BMSCs) for streptozotocin (STZ)-induced diabetic cystopathy in a rat model. In total, 68 male Sprague-Dawley rats were randomized into five groups: sham control (control group, n = 10); DCP model alone (DM group, n = 10); DCP rats intravenously treated with BMSCs (BMSC group, n = 16); DCP rats accepted adenoviral vector-infected BMSCs (Ad-null-BMSC group, n = 16) and DCP rats accepted ILK adenoviral vector-infected BMSCs (Ad-ILK-BMSC group, n = 16). Diabetic rats accepted cell transplantation in the experimental group (2 rats per group) were sacrificed for the bladder tissue on the third day, 7th day, and 14th day of treatment respectively ahead of schedule. At 4 weeks after treatment, all rats in five groups accepted urodynamic studies to evaluate bladder function and were sacrificed for bladder tissue.

Results

Our data showed that the underactive bladder function was significantly improved in DCP rats intravenously treated with ILK gene-modified BMSCs compared to those in the DM, BMSCs, and Ad-null-BMSC group. Meanwhile, we found that gene-modified BMSC treatment significantly promoted the activation of the AKT/GSK-3β pathway by increasing phosphorylation and led to the enhancement of survival. In addition, the expression levels of angiogenesis-related protein vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF), and stromal cell-derived factor-1 (SDF-1) were significantly higher in the Ad-ILK-BMSC group than that in the DM, BMSCs, and Ad-null-BMSC group as assessed by enzyme-linked immunosorbent assay and western blot. As two indicators of vascular endothelial cell markers, the expression of von Willebrand factor (vWF) and CD31 by western blot and immunofluorescent staining revealed that the percentage of the vascular area of the bladder tissue significantly increased in Ad-ILK-BMSC group compared with the BMSCs and Ad-null-BMSC group on the 14th day of treatment. Histological and immunohistochemical staining (hematoxylin and eosin (HE), vWF, Ki67, and TUNNEL) on the bladder tissue revealed statistically different results between groups.

Conclusion

ILK gene-modified BMSCs restored the bladder function and histological construction via promoting the process of angiogenesis and protecting cells from high glucose-associated apoptosis in STZ-induced DCP rat model, which provides a potential for the treatment of patients with DCP.

Grape seed proanthocyanidin extract alleviates urethral dysfunction in diabetic rats through modulating the NO-cGMP pathway

Oxidative stress is closely associated with the onset of diabetes mellitus (DM). Diabetic urethropathy is one of the most common complications of DM, but few studies have been conducted to investigate the role of oxidative stress in diabetic urethropathy. Grape seed proanthocyanidin extract (GSPE) has been previously reported to reduce oxidative injury. The present study aimed to investigate the role of oxidative stress and the protective effects of GSPE on urethral dysfunction using a streptozotocin-induced DM rat model. Female Wistar rats were divided into a control group (n=36), a DM group (n=36) and a DM + GSPE group (n=36). Urodynamic testing was performed using a PowerLab data acquisition device. The expression of neuronal nitric oxide synthase (nNOS), 3-nitrotyrosine and nuclear factor erythroid 2-related factor 2 (Nrf2) was determined using western blot analysis. The expression of 3-nitrotyrosine was also determined using immunohistochemistry. Nitric oxide (NO), cyclic guanosine monophosphate (cGMP), superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and malondialdehyde (MDA) were measured using commercial ELISA kits. A significant increase was observed in the intravesical pressure thresholds for inducing urethral relaxation and the urethral perfusion pressure nadir in DM rats compared with the control group. GSPE was observed to reverse the increase of these parameters compared with the DM group. In addition, GSPE could reverse the downregulation of nNOS, NO and cGMP expression, and the decreased activities of antioxidant enzymes (SOD and GSH-Px). GSPE reversed the upregulation of 3-nitrotyrosine and MDA in DM rats. GSPE also activated Nrf2, which is a key antioxidative transcription factor. The findings of the present study demonstrated that GSPE protects urethra function in DM rats through modulating the NO-cGMP signaling pathway. The protective roles of GSPE may be associated with activation of the Nrf2 defense pathway.