The Soluble Guanylyl Cyclase Activator BAY 60-2770 Ameliorates Overactive Bladder in Obese Mice

Nitric oxide signaling pathways in the normal and pathological bladder: Do they provide new pharmacological pathways?-ICI-RS 2023

AIMS

The nitric oxide (NO•)/soluble guanylate cyclase/cyclic-GMP (cGMP) signaling pathway is ubiquitous and regulates several functions in physiological systems as diverse as the vascular, nervous, and renal systems. However, its roles in determining normal and abnormal lower urinary tract functions are unclear. The aim was to identify potential therapeutic targets associated with this pathway to manage lower urinary tract functional disorders.

METHODS

This review summarizes a workshop held under the auspices of ICI-RS with a view to address these questions.

RESULTS

Four areas were addressed: NO• signaling to regulate neurotransmitter release to detrusor smooth muscle; its potential dual roles in alleviating and exacerbating inflammatory pathways; its ability to act as an antifibrotic mediator; and the control by nitrergic nerves of lower urinary tract vascular dynamics and the contractile performance of muscular regions of the bladder wall. Central to much of the discussion was the role of the NO• receptor, soluble guanylate cyclase (sGC) in regulating the generation of the enzyme product, the second messenger cGMP. The redox state of sGC is crucial in determining its enzymic activity and the role of a class of novel agents, sGC activators, to optimize activity and to potentially alleviate the consequences of lower urinary tract disorders was highlighted. In addition, the consequences of a functional relationship between nitrergic and sympathetic nerves to regulate vascular dynamics was discussed.

CONCLUSIONS

Several potential NO•-dependent drug targets in the lower urinary tract were identified that provide the basis for future research and translation to clinical trials.

Impact of intravascular hemolysis on functional and molecular alterations in the urinary bladder: implications for an overactive bladder in sickle cell disease

Patients with sickle cell disease (SCD) display an overactive bladder (OAB). Intravascular hemolysis in SCD is associated with various severe SCD complications. However, no experimental studies have evaluated the effect of intravascular hemolysis on bladder function. This study aimed to assess the effects of intravascular hemolysis on the micturition process and the contractile mechanisms of the detrusor smooth muscle (DSM) in a mouse model with phenylhydrazine (PHZ)-induced hemolysis; furthermore, it aimed to investigate the role of intravascular hemolysis in the dysfunction of nitric oxide (NO) signaling and in increasing oxidative stress in the bladder. Mice underwent a void spot assay, and DSM contractions were evaluated in organ baths. The PHZ group exhibited increased urinary frequency and increased void volumes. DSM contractile responses to carbachol, KCl, α-β-methylene-ATP, and EFS were increased in the PHZ group. Protein expression of phosphorylated endothelial NO synthase (eNOS) (Ser-1177), phosphorylated neuronal NO synthase (nNOS) (Ser-1417), and phosphorylated vasodilator-stimulated phosphoprotein (VASP) (Ser-239) decreased in the bladder of the PHZ group. Protein expression of oxidative stress markers, NOX-2, 3-NT, and 4-HNE, increased in the bladder of the PHZ group. Our study shows that intravascular hemolysis promotes voiding dysfunction correlated with alterations in the NO signaling pathway in the bladder, as evidenced by reduced levels of p-eNOS (Ser-1177), nNOS (Ser-1417), and p-VASP (Ser-239). The study also showed that intravascular hemolysis increases oxidative stress in the bladder. Our study indicates that intravascular hemolysis promotes an OAB phenotype similar to those observed in patients and mice with SCD.

Nitric Oxide Resistance in Priapism Associated with Sickle Cell Disease: Mechanisms, Therapeutic Challenges, and Future Directions

Patients with sickle cell disease (SCD) display priapism, a prolonged penile erection in the absence of sexual arousal. The current pharmacological treatments for SCD-associated priapism are limited and focused on acute interventions rather than prevention. Thus, there is an urgent need for new drug targets and preventive pharmacological therapies for this condition. This review focuses on the molecular mechanisms linked to the dysfunction of the NO-cyclic guanosine monophosphate (cGMP)-phosphodiesterase type 5 (PDE5) pathway implicated in SCD-associated priapism. In murine models of SCD, reduced nitric oxide (NO)-cGMP bioavailability in the corpus cavernosum is associated with elevated plasma hemoglobin levels, increased reactive oxygen species levels that inactive NO, and testosterone deficiency that leads to endothelial nitric oxide synthase downregulation. We discuss the consequences of the reduced cGMP-dependent PDE5 activity in response to these molecular changes, highlighting it as the primary pathophysiological mechanism leading to excessive corpus cavernosum relaxation, culminating in priapism. We also further discuss the impact of intravascular hemolysis on therapeutic approaches, present current pharmacological strategies targeting the NO-cGMP-PDE5 pathway in the penis, and identify potential pharmacological targets for future priapism therapies. In men with SCD and priapism, PDE5 inhibitor therapy and testosterone replacement have shown promising results. Recent preclinical research reported the beneficial effect of treatment with haptoglobin and NO donors. SIGNIFICANCE STATEMENT: This review discusses the molecular changes that reduce NO-cGMP bioavailability in the penis in SCD and highlights pharmacological targets and therapeutic strategies for the treatment of priapism, including PDE5 inhibitors, hormonal modulators, NO donors, hydroxyurea, soluble guanylate cyclase stimulators, haptoglobin, hemopexin, and antioxidants.

Methylglyoxal and Advanced Glycation End Products (AGEs): Targets for the Prevention and Treatment of Diabetes-Associated Bladder Dysfunction?

Methylglyoxal (MGO) is a highly reactive α-dicarbonyl compound formed endogenously from 3-carbon glycolytic intermediates. Methylglyoxal accumulated in plasma and urine of hyperglycemic and diabetic individuals acts as a potent peptide glycation molecule, giving rise to advanced glycation end products (AGEs) like arginine-derived hydroimidazolone (MG-H1) and carboxyethyl-lysine (CEL). Methylglyoxal-derived AGEs exert their effects mostly via activation of RAGE, a cell surface receptor that initiates multiple intracellular signaling pathways, favoring a pro-oxidant environment through NADPH oxidase activation and generation of high levels of reactive oxygen species (ROS). Diabetic bladder dysfunction is a bothersome urological complication in patients with poorly controlled diabetes mellitus and may comprise overactive bladder, urge incontinence, poor emptying, dribbling, incomplete emptying of the bladder, and urinary retention. Preclinical models of type 1 and type 2 diabetes have further confirmed the relationship between diabetes and voiding dysfunction. Interestingly, healthy mice supplemented with MGO for prolonged periods exhibit in vivo and in vitro bladder dysfunction, which is accompanied by increased AGE formation and RAGE expression, as well as by ROS overproduction in bladder tissues. Drugs reported to scavenge MGO and to inactivate AGEs like metformin, polyphenols, and alagebrium (ALT-711) have shown favorable outcomes on bladder dysfunction in diabetic obese leptin-deficient and MGO-exposed mice. Therefore, MGO, AGEs, and RAGE levels may be critically involved in the pathogenesis of bladder dysfunction in diabetic individuals. However, there are no clinical trials designed to test drugs that selectively inhibit the MGO-AGEs-RAGE signaling, aiming to reduce the manifestations of diabetes-associated bladder dysfunction. This review summarizes the current literature on the role of MGO-AGEs-RAGE-ROS axis in diabetes-associated bladder dysfunction. Drugs that directly inactivate MGO and ameliorate bladder dysfunction are also reviewed here.

Soluble guanylate cyclase stimulators and activators: new horizons in the treatment of priapism associated with sickle cell disease

Priapism, defined as a prolonged and often painful penile erection occurring without sexual stimulation or desire, is a common complication in sickle cell disease (SCD), affecting up to 48% of male patients. This condition presents significant clinical challenges and can lead to erectile dysfunction if not properly managed. Current pharmacological treatments for SCD-related priapism are primarily reactive rather than preventative, highlighting a gap in effective medical intervention strategies. A critical factor in developing priapism is the reduced basal bioavailability of nitric oxide (NO) and cyclic guanosine monophosphate (cGMP) in erectile tissues. New prevention strategies should ideally target the underlying pathophysiology of the disease. Compounds that stimulate and activate soluble guanylate cyclase (sGC) emerge as potential therapeutic candidates since these compounds have the property of inducing cGMP production by sGC. This review explores the potential of sGC stimulators and activators in treating priapism associated with SCD. We discuss the advantages of these agents in the face of the challenging pathophysiology of SCD. Additionally, the review underscores the impact of intravascular hemolysis and oxidative stress on priapism pathophysiology in SCD, areas in which sGC stimulators and activators may also have beneficial therapeutic effects.

Predictors of persistent overactive bladder following surgery for advanced pelvic organ prolapse

INTRODUCTION AND HYPOTHESIS

Reliable risk factors for persistent urgency following pelvic organ prolapse (POP) surgery are still unclear. We aimed to identify preoperative parameters related to persistent postoperative urgency in a cohort of women following surgery for POP stage 3-4 with concomitant overactive bladder (OAB).

METHODS

In this retrospective analysis, women with POP stage 3-4 and OAB who underwent POP repair during November 2012-December 2020 were included. Preoperative evaluation included history, Pelvic Organ Prolapse Quantification (POP-Q), multi-channel urodynamic studies and Pelvic Floor Distress Inventory (PFDI-20). Surgical procedures included: anterior and posterior colporrhaphy, sacrospinous ligament suspension, anterior vaginal wall mesh repair and robotic-assisted laparoscopic sacrocolpopexy. At the 12-month follow-up, urogynecological history, POP-Q evaluation, cough stress test and the PFDI-20 questionnaire were repeated.

RESULTS

One hundred seventy-three patients were included in the analysis. Resolution of urgency was observed in 56% of women. Variables associated with persistent postoperative urgency included body mass index (BMI) (27 kg/m² vs 25.7 kg/m², p = 0.04), preoperative increased daytime frequency (46.39% vs 61.84%, p = 0.05), urgency urinary incontinence (UUI) (51.46% vs 80.26%, p = 0.0001), detrusor overactivity (DO) (40.2% vs 61.84%, p = 0.009) and lower maximum flow rate on UDS (13.9 ml/s vs 15 ml/s, p = 0.04). Multivariate analysis confirmed preoperative DO (OR: 12.2 [95% CI: 1.4-16.6]; p = 0.01), preoperative UUI (OR 3.8 [95% CI: 1.3-11.0]; p = 0.008) and BMI > 25 kg/m² (OR 1.8 [95% CI: 1.1-7.2]; p = 0.04) as predictive factor for persistent urgency.

CONCLUSIONS

In women with advanced POP and OAB, being overweight, preoperative UUI and DO are related to persistent postoperative urgency. These findings will guide our future preoperative counseling and reinforce the role of UDS in POP management.

Effects of different diets used to induce obesity/metabolic syndrome on bladder function in rats

Preclinical and human studies on the relationship between obesity/metabolic syndrome (MetS) and lower urinary tract dysfunction (LUTD) are inconsistent. We compared the temporal effects of feeding four different diets used to induce obesity/MetS, including 60% fructose, 2% cholesterol +10% lard, 30% fructose + 20% lard, or 32.5% lard diet, up to 42 wk, on metabolic parameters and bladder function in male Sprague-Dawley rats. Rats fed a 30% fructose + 20% lard or 32.5% lard diet consumed less food (grams), but only the 32.5% lard diet group took in more calories. Feeding rats a 60% fructose or 30% fructose + 20% lard diet led to glucose intolerance and increased blood pressure. Higher body weight and increased cholesterol levels were observed in the rats maintained on a 2% cholesterol +10% lard diet, whereas exposure to a 32.5% lard diet affected most of the above parameters. Voiding behavior measurement showed that voiding frequency and the total voided volume were lower in the experimental diet groups except for the 30% fructose + 20% lard group. The mean voided volume was lower in the 30% fructose + 20% lard and 32.5% lard groups compared with the control group. Cystometric analysis revealed a decreased bladder capacity, mean voided volume, intermicturition interval, and compliance in the 32.5% lard diet group. In conclusion, experimental diets including 60% fructose, 30% fructose + 20% lard, or 2% cholesterol + 10% lard diet differently affected physiological and metabolic parameters and bladder function to a limited extent, while exposure to a 32.5% lard diet had a greater impact.

Low-energy shock wave therapy ameliorates ischemic-induced overactive bladder in a rat model

This study was to evaluate whether Low-energy shock wave therapy (LESW) improves ischemic-induced overactive bladder in rats and investigate its therapeutic mechanisms. Sixteen-week-old male Sprague-Dawley rats were divided into three groups: arterial injury (AI), AI with LESW (AI-SW), and control groups. LESW was irradiated in AI-SW during 20-23 weeks of age. At 24 weeks of age, conscious cystometry was performed (each n = 8). The voiding interval was shortened in AI (mean ± SEM: 5.1 ± 0.8 min) than in control (17.3 ± 3.0 min), whereas significant improvements were observed in AI-SW (14.9 ± 3.3 min). The bladder blood flow was significantly increased in AI-SW than in AI. Microarray analysis revealed higher gene expression of soluble guanylate cyclase (sGC) α1 and β1 in the bladder of AI-SW compared to AI. Protein expression of sGCα1 and sGCβ1 was higher in AI-SW and control groups than in AI. Cyclic guanosine monophosphate (cGMP) was elevated in AI-SW. As an early genetic response, vascular endothelial growth factor and CD31 were highly expressed 24 h after the first LESW. Suburothelial thinning observed in AI was restored in AI-SW. Activation of sGC-cGMP may play a therapeutic role of LESW in the functional recovery of the bladder.

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.

Benign prostatic hyperplasia/obstruction ameliorated using a soluble guanylate cyclase activator

Benign prostatic hyperplasia (BPH) is a feature of ageing males. Up to half demonstrate bladder outlet obstruction (BOO) with associated lower urinary tract symptoms (LUTS) including bladder overactivity. Current therapies to reduce obstruction, such as α1-adrenoceptor antagonists and 5α-reductase inhibitors, are not effective in all patients. The phosphodiesterase-5 inhibitor (PDE5I) tadalafil is also approved to treat BPH and LUTS, suggesting a role for nitric oxide (NO• ), soluble guanylate cyclase (sGC), and cGMP signalling pathways. However, PDE5I refractoriness can develop for reasons including nitrergic nerve damage and decreased NO• production, or inflammation-related oxidation of the sGC haem group, normally maintained in a reduced state by the cofactor cytochrome-b5-reductase 3 (CYB5R3). sGC activators, such as cinaciguat (BAY 58-2667), have been developed to enhance sGC activity in the absence of NO• or when sGC is oxidised. Accordingly, their effects on the prostate and LUT function of aged mice were evaluated. Aged mice (≥24 months) demonstrated a functional BPH/BOO phenotype, compared with adult animals (2-12 months), with low, delayed voiding responses and elevated intravesical pressures as measured by telemetric cystometry. This was consistent with outflow tract histological and molecular data that showed urethral constriction, increased prostate weight, greater collagen deposition, and cellular hyperplasia. All changes in aged animals were attenuated by daily oral treatment with cinaciguat for 2 weeks, without effect on serum testosterone levels. Cinaciguat had only transient (1 h) cardiovascular effects with oral gavage, suggesting a positive safety profile. The benefit of cinaciguat was suggested by its reversal of an overactive cystometric profile in CYB5R3 smooth muscle knockout mice that mirrors a profile of oxidative dysfunction where PDE5I may not be effective. Thus, the aged male mouse is a suitable model for BPH-induced BOO and cinaciguat has a demonstrated ability to reduce prostate-induced obstruction and consequent effects on bladder function. © 2021 The Pathological Society of Great Britain and Ireland.

Bladder Hyperactivity Induced by Oxidative Stress and Bladder Ischemia: A Review of Treatment Strategies with Antioxidants

Overactive bladder (OAB) syndrome, including frequency, urgency, nocturia and urgency incontinence, has a significantly negative impact on the quality-of-life scale (QoL) and can cause sufferer withdrawal from social activities. The occurrence of OAB can result from an imbalance between the production of pro-oxidants, such as free radicals and reactive species, and their elimination through protective mechanisms of antioxidant-induced oxidative stress. Several animal models, such as bladder ischemia/reperfusion (I/R), partial bladder outlet obstruction (PBOO) and ovarian hormone deficiency (OHD), have suggested that cyclic I/R during the micturition cycle induces oxidative stress, leading to bladder denervation, bladder afferent pathway sensitization and overexpression of bladder-damaging molecules, and finally resulting in bladder hyperactivity. Based on the results of previous animal experiments, the present review specifically focuses on four issues: (1) oxidative stress and antioxidant defense system; (2) oxidative stress in OAB and biomarkers of OAB; (3) OAB animal model; (4) potential nature/plant antioxidant treatment strategies for urinary dysfunction with OAB. Moreover, we organized the relationships between urinary dysfunction and oxidative stress biomarkers in urine, blood and bladder tissue. Reviewed information also revealed the summary of research findings for the effects of various antioxidants for treatment strategies for OAB.

New targets for overactive bladder-ICI-RS 2109

AIM

To review evidence for novel drug targets that can manage overactive bladder (OAB) symptoms.

METHODS

A think tank considered evidence from the literature and their own research experience to propose new drug targets in the urinary bladder to characterize their use to treat OAB.

RESULTS

Five classes of agents or cellular pathways were considered. (a) Cyclic nucleotide-dependent (cyclic adenosine monophosphate and cyclic guanosine monophosphate) pathways that modulate adenosine triphosphate release from motor nerves and urothelium. (b) Novel targets for β3 agonists, including the bladder wall vasculature and muscularis mucosa. (c) Several TRP channels (TRPV1 , TRPV4 , TRPA1 , and TRPM4 ) and their modulators in affecting detrusor overactivity. (d) Small conductance Ca2+ -activated K+ channels and their influence on spontaneous contractions. (e) Antifibrosis agents that act to modulate directly or indirectly the TGF-β pathway-the canonical fibrosis pathway.

CONCLUSIONS

The specificity of action remains a consideration if particular classes of agents can be considered for future development as receptors or pathways that mediate actions of the above mentioned potential agents are distributed among most organ systems. The tasks are to determine more detail of the pathological changes that occur in the OAB and how the specificity of potential drugs may be directed to bladder pathological changes. An important conclusion was that the storage, not the voiding, phase in the micturition cycle should be investigated and potential targets lie in the whole range of tissue in the bladder wall and not just detrusor.

Activation of PKG and Akt Is Required for Cardioprotection by Ramelteon-Induced Preconditioning and Is Located Upstream of mKCa-Channels

Ramelteon is a Melatonin 1 (MT1)—and Melatonin 2 (MT2)—receptor agonist conferring cardioprotection by pharmacologic preconditioning. While activation of mitochondrial calcium-sensitive potassium (mK_Ca)-channels is involved in this protective mechanism, the specific upstream signaling pathway of Ramelteon-induced cardioprotection is unknown. In the present study, we (1) investigated whether Ramelteon-induced cardioprotection involves activation of protein kinase G (PKG) and/or protein kinase B (Akt) and (2) determined the precise sequence of PKG and Akt in the signal transduction pathway of Ramelteon-induced preconditioning. Hearts of male Wistar rats were randomized and placed on a Langendorff system, perfused with Krebs–Henseleit buffer at a constant pressure of 80 mmHg. All hearts were subjected to 33 min of global ischemia and 60 min of reperfusion. Before ischemia, hearts were perfused with Ramelteon (Ram) with or without the PKG or Akt inhibitor KT5823 and MK2206, respectively (KT5823 + Ram, KT5823, MK2206 + Ram, MK2206). To determine the precise signaling sequence, subsequent experiments were conducted with the guanylate cyclase activator BAY60-2770 and the mK_Ca-channel activator NS1619. Infarct size was determined by 2,3,5-triphenyltetrazolium chloride (TTC) staining. Ramelteon-induced infarct size reduction was completely blocked by KT5823 (p = 0.0012) and MK2206 (p = 0.0005). MK2206 with Ramelteon combined with BAY60-2770 reduced infarct size significantly (p = 0.0014) indicating that PKG activation takes place after Akt. Ramelteon and KT5823 (p = 0.0063) or MK2206 (p = 0.006) respectively combined with NS1619 also significantly reduced infarct size, indicating that PKG and Akt are located upstream of mK_Ca-channels. This study shows for the first time that Ramelteon-induced preconditioning (1) involves activation of PKG and Akt; (2) PKG is located downstream of Akt and (3) both enzymes are located upstream of mK_Ca-channels in the signal transduction pathway.

Chronic high-fat diet decreased detrusor mitochondrial respiration and increased nerve-mediated contractions

AIMS

To assess the impact of chronic high-fat diet (HFD) on behavioral voiding patterns, detrusor contractility, and smooth muscle mitochondrial function in male mice.

MATERIALS AND METHODS

Male C57BL/6J mice (6 weeks) were fed a control or HFD for 20 weeks. Bladder function was assessed by void spot assays. Bladders were collected and detrusor contractility to carbachol (10^-9 -10^-5  M), and electrical field stimulation (EFS, 0.5-32 Hz) in the presence and absence of atropine was measured. Homogenized detrusor samples were placed in oxygraphs to assess the rate of oxygen consumption of the mitochondria within the detrusor in the presence of different substrates. Mitochondrial hydrogen peroxide (H₂ O₂ ) emission was measured fluorometrically. Detrusor citrate synthase activity was measured via enzyme activity kit and Western blots assessed the electron transport chain (ETC) protein content.

RESULTS

HFD significantly increased body weight, adiposity, and blood glucose levels. HFD mice demonstrated increased voiding frequency and increased EFS-induced detrusor contractility. There were no changes in detrusor relaxation or cholinergic-medicated contraction. Mitochondrial respiration was decreased with HFD and H₂ O ₂ emission was increased. The relative amount of mitochondria in the detrusor was similar between groups. However, ETC complexes V and III were increased following HFD.

CONCLUSIONS

Chronic HFD increased adiposity, lead to more frequent voiding, and enhanced EFS-mediated detrusor contractions. Mitochondrial respiration was decreased and H₂ O ₂ emission increased following HFD. Further research is required to determine if alterations in mitochondrial function could play a role in the development of HFD-induced bladder dysfunction.

Tadalafil for the treatment of benign prostatic hyperplasia

INTRODUCTION

In men, lower urinary tract symptoms (LUTS) are primarily attributed to benign prostatic hyperplasia (BPH). Therapeutic options are targeted to relax prostate smooth muscle and/or reduce prostate enlargement. Areas covered: This article reviews the major preclinical and clinical data on PDE5 inhibitors with a specific focus on tadalafil. It includes details of the role of the nitric oxide (NO)-cyclic guanosine monophosphate (cGMP) - PDE5 pathway in the LUT organs (bladder and prostate) in addition to the available data on tadalafil in patients with LUTS secondary to BPH with or without erectile dysfunction (ED). Expert opinion: Preclinical and clinical data have clearly demonstrated that PDE5 inhibitors induce bladder and prostate relaxation, which contributes to the improvement seen in storage symptoms in both animal models of bladder and prostate hypercontractility. Tadalafil is effective both as a monotherapy and add-on therapy in patients with LUTS secondary to BPH. Furthermore, as LUTS-BPH and ED are urological disorders that commonly coexist in aging men, tadalafil is more advantageous than α1-adrenoceptors and should be used as the first option. Tadalafil is a safe and tolerable therapy and unlike α1- adrenoceptors and 5-alpha reductase inhibitors, which can cause sexual dysfunctions, tadalafil improves sexual function.

Comparative Studies of the Dynamics Effects of BAY60-2770 and BAY58-2667 Binding with Human and Bacterial H-NOX Domains

Soluble guanylate cyclase (sGC) is a key enzyme implicated in various physiological processes such as vasodilation, thrombosis and platelet aggregation. The enzyme’s Heme-Nitric oxide/Oxygen (H-NOX) binding domain is the only sensor of nitric oxide (NO) in humans, which on binding with NO activates sGC to produce the second messenger cGMP. H-NOX is thus a hot target for drug design programs. BAY60-2770 and BAY58-2667 are two widely studied activators of sGC. Here we present comparative molecular dynamics studies to understand the molecular details characterizing the binding of BAY60-2770 and BAY58-2667 with the human H-NOX (hH-NOX) and bacterial H-NOX (bH-NOX) domains. HartreeFock method was used for parametrization of both the activators. A 50 ns molecular dynamics (MD) simulation was run to identify the functionally critical regions of the H-NOX domains. The CPPTRAJ module was used for analysis. BAY60-2770 on binding with bH-NOX, triggered rotational movement in signaling helix F and significant dynamicity in loops α and β, but in hH-NOX domain the compound showed relatively lesser aforementioned structural fluctuations. Conversely, hH-NOX ligated BAY58-2667 experienced highest transitions in its helix F due to electrostatic interactions with D84, T85 and R88 residues which are not conserved in bH-NOX. These conformational transformations might be essential to communicate with downstream PAS, CC and cyclase domains of sGC. Comparative MD studies revealed that BAY bound bHNOX dynamics varied from that of hH-NOX, plausibly due to some key residues such as R40, F74 and Y112 which are not conserved in bacteria. These findings will help to the design of novel drug leads to cure diseases associated to human sGC.

Inhibition of Multidrug Resistance Proteins by MK 571 Enhances Bladder, Prostate, and Urethra Relaxation through cAMP or cGMP Accumulation

The biologic effect of cAMP and cGMP is terminated by phosphodiesterases and multidrug resistance proteins MRP4 and MRP5, which pump cyclic nucleotides out of the cell. Therefore, this study aimed to characterize the role of MRP inhibitor, MK 571 (3-[[[3-[(1E)-2-(7-chloro-2-quinolinyl)ethenyl]phenyl][[3-(dimethylamino)-3-oxopropyl]thio]methyl]thio]propanoic acid), in the bladder, prostate, and urethra of male mice by means of functional assays, protein expression, and cyclic nucleotide quantification. The cumulative addition of MK 571 (1-30 µM) produced only small relaxation responses (approximately 25%) in all studied tissues. In the bladder, isoprenaline/fenoterol and forskolin concentration-dependently relaxed and MK 571 (20 µM) increased the maximal response values by 37% and 24%, respectively. When MK 571 was coincubated with fenoterol or forskolin, intracellular levels of cAMP and protein expression of phospho-vasodilator-stimulated phosphoprotein (p-VASP) Ser157 were significantly greater compared with bladders stimulated with fenoterol or forskolin alone. In the prostate and urethra, sodium nitroprusside concentration-dependently relaxed and MK 571 (20 µM) significantly increased relaxation responses by 70% and 56%, respectively, accompanied by greater intracellular levels of cGMP and protein expression of p-VASP Ser239 in the prostate. Tadalafil and BAY 41-2272 (5-cyclopropyl-2-[1-[(2-fluorophenyl)methyl]-1H-pyrazolo[3,4-b]pyridin-3-yl]-4-pyrimidinamine) also relaxed the prostate and urethra, respectively, and MK 571 markedly enhanced this response. The stable analog of cGMP (8-Br-cGMP) induced concentration-dependent relaxation responses in the prostate and urethra, and MK 571 significantly increased the relaxation response. In conclusion, to our knowledge, this is the first study to show that efflux transporters are physiologically active in the bladder, prostate, and urethra to control intracellular levels of cAMP or cGMP.

Influence of the periprostatic adipose tissue in obesity-associated mouse urethral dysfunction and oxidative stress: Effect of resveratrol treatment

Obese mice display overactive bladder (OAB) associated with impaired urethra smooth muscle (USM) function. In this study, we evaluated the role of the adipose tissue surrounding the urethra and prostate in obese mice (here referred as periprostatic adipose tissue; PPAT) to the USM dysfunction. Male C57BL6/JUnib mice fed with either a standard-chow or high-fat diet to induce obesity were used. In PPAT, histological analysis, and qPCR analysis for gp91phox, tumor necrosis factor-α (TNF-α) and superoxide dismutase (SOD) were conducted. In USM, concentration-response curves to contractile and relaxing agents, as well as measurements of reactive-oxygen species and nitric oxide (NO) levels were performed. The higher PPAT area in obese mice was accompanied by augmented gp91phox (NOX2) and TNF-α expressions, together with decreased SOD1 expression. In USM of obese group, the contractile responses to phenylephrine and vasopressin were increased, whereas the relaxations induced with glyceryl trinitrate were reduced. The reactive-oxygen species and NO levels in USM of obese mice were increased and decreased, respectively. A higher SOD expression was also detected in obese group whilst no changes in the gp91phox levels were observed. We next evaluated the effects of the antioxidant resveratrol (100 mg/kg/day, two-weeks, PO) in the functional alterations and NO levels of obese mice. Resveratrol treatment in obese mice reversed both the functional USM dysfunction and the reduced NO production. Our data show that PPAT exerts a local inflammatory response and increases oxidative stress that lead to urethral dysfunction. Resveratrol could be an auxiliary option to prevent obesity-associated urethral dysfunction.

Oxidative stress and its possible relation to lower urinary tract functional pathology

Oxidative stress is considered to reflect an imbalance between the systemic manifestation of reactive oxygen and nitrogen species (RONS) and a biological system's ability to readily detoxify the reactive intermediates or to repair the resulting damage. RONS are not only harmful agents that cause oxidative damage in pathologies; they also have important roles as regulatory agents in a range of biological phenomena. They are normally generated as by-products of oxygen metabolism; however, environmental stressors (i.e., ultraviolet radiation, ionizing radiations, pollutants, heavy metal, and xenobiotics) contribute to greatly increase RONS production. Several antioxidants have been exploited in recent years for their actual or supposed beneficial effect against oxidative stress, but to date, none has been approved for any indication because they have not met the criteria of efficacy for drug approval. The present review discusses the concept of oxidative stress, how to measure it, how to prevent it, and its occurrence in different organ systems with special reference to the lower urinary tract.

Cardioprotective effects of PKG activation by soluble GC activator, BAY 60-2770, in ischemia-reperfusion-injured rat hearts

Soluble guanylate cyclase (sGC) has been suggested as a therapeutic target for cardiac ischemia-reperfusion (IR) injury. Until now, the molecular mechanism of BAY 60-2770, a sGC activator, in cardiac IR injury has not been assessed. To identify the cardioprotective effects of BAY 60-2770 in IR-injured rat hearts, IR injury was established by occlusion of LAD for 40 min and reperfusion for 7 days, and the effects of BAY 60-2770 on myocardial protection were assessed by echocardiography and TTC staining. 5 nM and 5 μM of BAY 60-2770 were perfused into isolated rat hearts in a Langendorff system. After 10- or 30-min reperfusion with BAY 60-2770, cGMP and cAMP concentrations and PKG activation status were examined. Hearts were also perfused with 1 μM KT5823 or 100 μM 5-HD in conjunction with 5 nM Bay 60-2770 to evaluate the protective role of PKG. Mitochondrial oxidative stress was investigated under hypoxia-reoxygenation in H9c2 cells. In IR-injured rat hearts, BAY 60-2770 oral administration reduced infarct size by TTC staining and improved left ventricular function by echocardiography. Tissue samples from BAY 60-2770-perfused hearts had approximately two-fold higher cGMP levels. BAY 60-2770 increased PKG activity in the myocardium, and the reduced infarct area by BAY 60-2770 was abrogated by KT-5823 in isolated myocardium. In H9c2 cardiac myoblasts, hypoxia-reoxygenation-mediated mitochondrial ROS generation was diminished with BAY 60-2770 treatment, but was recovered by pretreatment with KT-5823. BAY 60-2770 demonstrated a protective effect against cardiac IR injury via mitoKATP opening and decreased mitoROS by PKG activation. BAY 60-2770 has a protective effect against cardiac IR injury via mitoKATP opening and decreased mitoROS by PKG activation. These results demonstrated that BAY 60-2770 may be used as a therapeutic agent for cardiac IR injury.

Path of translational discovery of urological complications of obesity and diabetes

Diabetes mellitus (DM) is a prevalent chronic disease. Type 1 DM (T1DM) is a metabolic disorder that is characterized by hyperglycemia in the context of absolute lack of insulin, whereas type 2 DM (T2DM) is due to insulin resistance-related relative insulin deficiency. In comparison with T1DM, T2DM is more complex. The natural history of T2DM in most patients typically involves a course of obesity to impaired glucose tolerance, to insulin resistance, to hyperinsulinemia, to hyperglycemia, and finally to insulin deficiency. Obesity is a risk factor of T2DM. Diabetes causes some serious microvascular and macrovascular complications, such as retinopathy, nephropathy, neuropathy, angiopathy and stroke. Urological complications of obesity and diabetes (UCOD) affect quality of life, but are not well investigated. The urological complications in T1DM and T2DM are different. In addition, obesity itself affects the lower urinary tract. The aim of this perspective is to review the available data, combined with the experience of our research teams, who have spent a good part of last decade on studies of association between DM and lower urinary tract symptoms (LUTS) with the aim of bringing more focus to the future scientific exploration of UCOD. We focus on the most commonly seen urological complications, urinary incontinence, bladder dysfunction, and LUTS, in obesity and diabetes. Knowledge of these associations will lead to a better understanding of the pathophysiology underlying UCOD and hopefully assist urologists in the clinical management of obese or diabetic patients with LUTS.

Obesity-initiated metabolic syndrome promotes urinary voiding dysfunction in a mouse model

OBJECTIVE

Accumulating evidences suggests that obesity and metabolic syndrome (MetS) contribute towards lower urinary tract symptoms (LUTS) through alterations in the phenotype of bladder and prostate gland. Clinical studies indicate a link between MetS and LUTS. Nevertheless, there is lack of suitable animal model(s) which could illustrate an association linking obesity to LUTS. We examined the lower urinary tract function in an obesity-initiated MetS mouse model.

METHODS

Male C57BL/6N wild-type and obese B6.V-Lepob/J maintained on regular diet for 28 weeks were subjected to the assessment of body weight (BW), body length (BL), waist circumference (WC), body mass index (BMI), blood glucose (BG), plasma insulin (INS), plasma leptin (LEP), total cholesterol (CHO), free fatty acid (FFA), and measurement of urinary functions. Whole animal peritoneal and subcutaneous adipose tissue measurements as well as prostate and bladder volumes were analyzed by MRI followed by histological evaluation. These parameters were used to draw correlations between MetS and LUTS.

RESULTS

Obesity parameters such as BW, WC, and BMI were significantly higher in B6.V-Lepob/J mice compared to C57BL/6N mice (P < 0.01). Higher levels of total CHO and FFA were noted in B6.V-Lepob/J mice than C57BL/6N mice (P < 0.05). These results were concurrent with frequency, lower average urine volume and other urinary voiding dysfunctions in B6.V-Lepob/J mice. MRI assessments demonstrate marked increase in body fat and prostate volume in these mice. Compared to C57BL/6N mice, histological analysis of the prostate from B6.V-Lepob/J mice showed increased proliferation, gland crowding, and infiltration of immune cells in the stroma; whereas the bladder urothelium was slightly thicker and appears more proliferative in these mice. The regression and correlation analysis indicate that peritoneal fat (R = 0.853; P < 0.02), CHO (R = 0.729; P < 0.001), BG (R = 0.712; P < 0.001) and prostate volume (R = 0.706; P < 0.023) strongly correlate with LUTS whereas BMI, WC, INS, and FFA moderately correlate with the prevalence of bladder dysfunction.

CONCLUSION

Our results suggest that LUTS may be attributable in part to obesity and MetS. Validation of an in vivo model may lead to understand the underlying pathophysiological mechanisms of obesity-related LUTS in humans. Prostate 76:964-976, 2016. © 2016 Wiley Periodicals, Inc.

The Endothelium-Dependent Nitric Oxide-cGMP Pathway

Nitric oxide (NO)-cyclic 3'-5' guanosine monophosphate (cGMP) signaling plays a critical role on smooth muscle tone, platelet activity, cardiac contractility, renal function and fluid balance, and cell growth. Studies of the 1990s established endothelium dysfunction as one of the major causes of cardiovascular diseases. Therapeutic strategies that benefit NO bioavailability have been applied in clinical medicine extensively. Basic and clinical studies of cGMP regulation through activation of soluble guanylyl cyclase (sGC) or inhibition of cyclic nucleotide phosphodiesterase type 5 (PDE5) have resulted in effective therapies for pulmonary hypertension, erectile dysfunction, and more recently benign prostatic hyperplasia. This section reviews (1) how endothelial dysfunction and NO deficiency lead to cardiovascular diseases, (2) how soluble cGMP regulation leads to beneficial effects on disorders of the circulation system, and (3) the epigenetic regulation of NO-sGC pathway components in the cardiovascular system. In conclusion, the discovery of the NO-cGMP pathway revolutionized the comprehension of pathophysiological mechanisms involved in cardiovascular and other diseases. However, considering the expression "from bench to bedside" the therapeutic alternatives targeting NO-cGMP did not immediately follow the marked biochemical and pathophysiological revolution. Some therapeutic options have been effective and released on the market for pulmonary hypertension and erectile dysfunction such as inhaled NO, PDE5 inhibitors, and recently sGC stimulators. The therapeutic armamentarium for many other disorders is expected in the near future. There are currently numerous active basic and clinical research programs in universities and industries attempting to develop novel therapies for many diseases and medical applications.

Chronic treatment with resveratrol improves overactive bladder in obese mice via antioxidant activity

The objective of the present work was to evaluate whether oral intake with resveratrol ameliorates overactive bladder in high-fat fed mice. Male C57BL6 mice fed with standard chow or high-fat diet to induce obesity received a two-week therapy with resveratrol (100mg/kg, given as a daily gavage). Weight and metabolic profile, together with cystometry and in vitro bladder contractions were evaluated. Measurements of gp91phox and SOD1 mRNA expressions and reactive-oxygen species (ROS) in bladder tissues, and serum TBARS were performed. Obese mice exhibited increases in body weight and epididymal fat mass, which were significantly reduced by oral treatment with resveratrol. Cystometric study in obese mice showed increases in non-voiding contractions, post-voiding pressure and voiding frequency that were reversed by resveratrol treatment. Likewise, the in vitro bladder overactivity in response to electrical-field stimulation (80V, 1-32Hz) or carbachol (1nM to 10mM) were normalized by resveratrol. The gp91phox and SOD1 mRNA expressions in bladder tissues were markedly higher in obese mice compared with lean group. In addition, ROS levels in bladder tissues and serum lipid peroxidation (TBARS assay) were markedly higher in obese compared with lean mice, all of which were reduced by resveratrol treatment. In lean group, resveratrol had no effect in any parameter evaluated. Our results show that two-week therapy of obese mice with resveratrol reduces the systemic and bladder oxidative stress, and greatly ameliorated the cystometry alterations and in vitro bladder overactivity. Resveratrol treatment could be an option to prevent obesity-associated overactive bladder.

Activation of soluble guanylyl cyclase by BAY 58-2667 improves bladder function in cyclophosphamide-induced cystitis in mice

Activators of soluble guanylyl cyclase (sGC) interact directly with its prosthetic heme group, enhancing the enzyme responsiveness in pathological conditions. This study aimed to evaluate the effects of the sGC activator BAY 58-2667 on voiding dysfunction, protein expressions of α1 and β1 sGC subunits and cGMP levels in the bladder tissues after cyclophosphamide (CYP) exposure. Female C57BL/6 mice (20-25 g) were injected with CYP (300 mg/kg ip) to induce cystitis. Mice were pretreated or not with BAY 58-2667 (1 mg/kg, gavage), given 1 h before CYP injection. The micturition patterns and in vitro bladder contractions were evaluated at 24 h. In freely moving mice, the CYP injection produced reduced the micturition volume and increased the number of urine spots. Cystometric recordings in CYP-injected mice revealed significant increases in basal pressure, voiding frequency, and nonvoiding contractions (NVCs), along with decreases in bladder capacity, intercontraction interval, and compliance. BAY 58-2667 significantly prevented the micturition alterations observed in both freely moving mice and cystometry and normalized the reduced in vitro carbachol-induced contractions in the CYP group. Reduced protein expressions of α1 and β1 sGC subunits and of cGMP levels were observed in the CYP group, all of which were prevented by BAY 58-2667. CYP exposure significantly increased reactive-oxygen species (ROS) generation in both detrusor and urothelium, and this was normalized by BAY 58-2667. The increased myeloperoxidase and cyclooxygenase-2 activities in the bladders of the CYP group remained unchanged by BAY 58-2667. Activators of sGC may constitute a novel and promising therapeutic approach for management of interstitial cystitis.

Therapeutic modulation of urinary bladder function: multiple targets at multiple levels

Storage dysfunction of the urinary bladder, specifically overactive bladder syndrome, is a condition that occurs frequently in the general population. Historically, pathophysiological and treatment concepts related to overactive bladder have focused on smooth muscle cells. Although these are the central effector, numerous anatomic structures are involved in their regulation, including the urothelium, afferent and efferent nerves, and the central nervous system. Each of these structures involves receptors for—and the urothelium itself also releases—many mediators. Moreover, hypoperfusion, hypertrophy, and fibrosis can affect bladder function. Established treatments such as muscarinic antagonists, β-adrenoceptor agonists, and onabotulinumtoxinA each work in part through their effects on the urothelium and afferent nerves, as do α1-adrenoceptor antagonists in the treatment of voiding dysfunction associated with benign prostatic hyperplasia; however, none of these treatments are specifically targeted to the urothelium and afferent nerves. It remains to be explored whether future treatments that specifically act at one of these structures will provide a therapeutic advantage.

Prolonged therapy with the soluble guanylyl cyclase activator BAY 60-2770 restores the erectile function in obese mice

INTRODUCTION

Cardiovascular and endocrine-metabolic diseases associated with increased oxidative stress such as obesity lead to erectile dysfunction (ED). Activators of soluble guanylyl cyclase (sGC) such as BAY 60-2770 reactivate the heme-oxidized sGC in vascular diseases.

AIM

This study aimed to evaluate the effects of 2-week oral intake with BAY 60-2270 on a murine model of obesity-associated ED.

METHODS

C57BL/6 male mice were fed for 12 weeks with standard chow or high-fat diet. Lean and obese mice were treated with BAY 60-2770 (1 mg/kg/day, 2 weeks).

MAIN OUTCOME MEASURES

Measurements of intracavernosal pressure (ICP), along with acetylcholine (10(-9) to 10(-5)  M) and electrical field stimulation (EFS; 4-10 Hz)-induced corpus cavernosum relaxations in vitro, were obtained. Levels of cyclic guanosine monophosphate (cGMP), reactive oxygen species (ROS), and sGC protein expressions in cavernosal tissues were measured.

RESULTS

Cavernous nerve stimulation caused frequency-dependent ICP increases, which were significantly lower in obese compared with lean mice (P < 0.05). Two-week therapy with BAY 60-2770 fully reversed the decreased ICP in obese group. Acetylcholine-induced cavernosal relaxations were 45% lower (P < 0.001) in obese mice, which were fully restored by BAY 60-2770 treatment. Likewise, the EFS-induced relaxations in obese mice were restored by BAY 60-2770. Basal cGMP content in erectile tissue was 68% lower (P < 0.05) in obese mice, an effect normalized by BAY 60-2770. Levels of ROS were 52% higher (P < 0.05) whereas protein expression of α1 sGC subunit was reduced in cavernosal tissue of obese mice, both of which were normalized by BAY 60-2770. In lean group, BAY 60-2770 did not significantly affect any functional, biochemical, or molecular parameter analyzed.

CONCLUSIONS

Two-week therapy with BAY 60-2770 restores the erectile function in obese mice that is associated with reduced ROS levels, up-regulation of α1 sGC subunit, and increased cGMP levels in the erectile tissue.

Soluble guanylyl cyclase (sGC) degradation and impairment of nitric oxide-mediated responses in urethra from obese mice: reversal by the sGC activator BAY 60-2770

Obesity has emerged as a major contributing risk factor for overactive bladder (OAB), but no study examined urethral smooth muscle (USM) dysfunction as a predisposing factor to obesity-induced OAB. This study investigated the USM relaxant machinery in obese mice and whether soluble guanylyl cyclase (sGC) activation with BAY 60-2770 [acid 4-({(4-carboxybutyl) [2-(5-fluoro-2-{[4-(trifluoromethyl) biphenyl-4-yl] methoxy} phenyl) ethyl] amino} methyl) benzoic] rescues the urethral reactivity through improvement of sGC-cGMP (cyclic guanosine monophosphate) signaling. Male C57BL/6 mice were fed for 12 weeks with a high-fat diet to induce obesity. Separate groups of animals were treated with BAY 60-2770 (1 mg/kg per day for 2 weeks). Functional assays and measurements of cGMP, reactive-oxygen species (ROS), and sGC protein expression in USM were determined. USM relaxations induced by NO (acidified sodium nitrite), NO donors (S-nitrosoglutathione and glyceryl trinitrate), and BAY 41-2272 [5-cyclopropyl-2-[1-(2-fluoro-benzyl)-1H-pyrazolo[3,4-b]pyridin-3-yl]-pyrimidin-4-ylamine] (sGC stimulator) were markedly reduced in obese compared with lean mice. In contrast, USM relaxations induced by BAY 60-2770 (sGC activator) were 43% greater in obese mice (P < 0.05), which was accompanied by increases in cGMP levels. Oxidation of sGC with ODQ [1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one] (10 μM) potentiated BAY 60-2770-induced USM responses in the lean group. Long-term oral BAY 60-2770 administration fully prevented the impairment of USM relaxations in obese mice. Reactive-oxygen species (ROS) production was enhanced, but protein expression of β1 second guanylate cyclase subunit was reduced in USM from obese mice, both of which were restored by BAY 60-2770 treatment. In conclusion, impaired USM relaxation in obese mice is associated with ROS generation and down-regulation of sGC-cGMP signaling. Prevention of sGC degradation by BAY 60-2770 ameliorates the impairment of urethral relaxations in obese mice.