Effect of the phytotherapeutic agent eviprostat on the bladder in a rat model of bladder overdistension/emptying

Medicinal plants and natural products for treating overactive bladder

BACKGROUND

Overactive bladder (OAB) presents a high prevalence of 16-18% worldwide. The pathophysiology of OAB is still poorly understood while effective therapy or countermeasure are very limited. On the other hand, medicinal plants and herbal remedies have been utilized for treating lower urinary tract symptoms (LUTS) in both Eastern and Western cultures since ancient times. In recent years, accumulating progress has also been made in OAB treatment research by using medicinal plants.

METHODS

Relevant literature on the studies of medicinal plants and herbs used to treat OAB was reviewed. The medicinal plants were summarized and categorized into two groups, single-herb medications and herbal formulations.

RESULTS

The present review has summarized current understanding of OAB's pathophysiology, its available treatments and new drug targets. Medicinal plants and natural products which have been used or have shown potential for OAB treatment were updated and comprehensively categorized. Studies on a wide variety of medicinal plants showed promising results, although only a few phytochemicals have been isolated and identified. Until now, none of these herbal compounds have been further developed into clinical therapeutics for OAB.

CONCLUSIONS

This review provides the basis for discovering and designing new phytopharmaceutical candidates with effective and well-tolerated properties to treat OAB. Increasing evidences indicate new strategies with alternative herbal treatment for OAB have high efficacy and safety, showing great promise for their clinical use. Future studies in a rigorously designed controlled manner will be beneficial to further support the eligibility of herbal treatment as OAB therapeutics.

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.

The pretreatment of rats with nebivolol ameliorates bladder contractile dysfunction caused by ischemia-reperfusion injury

OBJECTIVE

The present study aimed to investigate the protective effect of nebivolol in the bladder isolated from rats exposed to ischemia-reperfusion (IR) injury.

METHODS

Sprague-Dawley rats were divided into control, IR, and nebivolol+IR groups. In the nebivolol+IR group, nebivolol was administered (0.4 mg/kg, subcutaneous) in rats prior to IR insult. At the end of the experimental protocol, the urinary bladder was rapidly isolated and bladder strips were mounted in an organ bath. After the equilibration period, potassium chloride (KCl, 20-100 mM) or carbachol (0.01-10 μM) was cumulatively added to the organ bath to generate cumulative concentration-response curves (CCRCs). Oxidative stress and interleukin 6 (IL-6) levels were also evaluated in the bladder tissue.

RESULTS

The CCRCs of KCl and carbachol were significantly reduced in the IR group compared to those of the control, and this inhibition was reversed by the pretreatment of rats with nebivolol (P < .05). The IR group's total antioxidant status was significantly lower with a concomitant increase in IL-6 levels than that of the control and nebivolol+IR groups (P < .05).

CONCLUSIONS

The present study indicates that pretreatment of rats with nebivolol (0.4 mg/kg) could improve bladder contractile dysfunction caused by IR injury through suppression of increased oxidative stress and IL-6 levels.

The effect of mirabegron on bladder blood flow in a rat model of bladder outlet obstruction

PURPOSE

To evaluate the effects of mirabegron on bladder blood flow in a rat model of bladder outlet obstruction (BOO).

METHODS

Adult female Sprague-Dawley rats were divided into three groups based on whether they underwent a sham operation (sham group) or an operation to establish partial BOO (BOO and BOO + mirabegron groups). The BOO + mirabegron group was treated with mirabegron (0.3 mg/kg/h, subcutaneously) for 14 days. Subsequently, we performed continuous cystometry, bladder blood flow measurements with a 2D laser blood flow imager, hematoxylin-eosin staining of the bladder tissue, and malondialdehyde (MDA) measurements in the bladder tissue.

RESULTS

Cystometry revealed significantly higher peak pressure, more residual urine volume, and lower voiding efficiency in the BOO and BOO + mirabegron groups than in the sham group. The BOO + mirabegron group had significantly fewer non-voiding contractions (NVCs) than the BOO group, while the latter had more frequent NVCs than the sham group. The BOO and BOO + mirabegron groups had significantly decreased bladder blood flow than the sham group, whereas the BOO + mirabegron group showed significantly increased bladder blood flow than the BOO group. The bladder tissue in the BOO group contained more hypertrophic detrusor muscle compared to the sham group, while mirabegron treatment suppressed detrusor hypertrophy. The MDA levels were significantly higher in the BOO group than in the BOO + mirabegron and sham groups.

CONCLUSION

Mirabegron treatment significantly improved BOO-induced bladder dysfunction through the amelioration of bladder blood flow.

A Review of Oxidative Stress and Urinary Dysfunction Caused by Bladder Outlet Obstruction and Treatments Using Antioxidants

Urinary dysfunction is a common pathological condition that can significantly decrease the quality of life. Bladder outlet obstruction (BOO) is a major cause of urinary dysfunction, and various lower urinary tract diseases including benign prostatic hyperplasia and urethral stricture disease cause BOO. According to the results of a variety of animal experiments on partial BOO (PBOO), there is a general agreement that ischemic conditions and repeated ischemia/reperfusion of the bladder are closely associated with BOO-induced bladder damage, and that increased oxidative stress by ischemia/reperfusion plays a crucial role in the pathological mechanisms underlying urinary dysfunction. Changes in biomarkers of oxidative stress in PBOO animal models support this association between oxidative stress and urinary dysfunction. Oxidative stress is defined as an imbalance between the production of pro-oxidants, such as free radicals and reactive species, and their elimination through protective mechanisms of antioxidants. Therefore, organizing the knowledge on the state of oxidative stress, changes in biomarkers, and biological roles of antioxidants in systemic and bladder tissues is essential to understand the detailed pathological characteristics of the urinary dysfunction caused by PBOO. Furthermore, information on drugs and supplements that have antioxidant effects is important for defining treatment strategies for urinary dysfunction with PBOO. In this review, we paid special attention to the following three issues; (1) changes in oxidative stress, including its biomarkers, (2) antioxidant status, and (3) previous reports on treatment strategies involving agents with antioxidative activity for urinary dysfunction caused by BOO. In particular, we provide systematic information on the detailed mechanisms underlying the antioxidative effects of agents used to treat PBOO. In addition, we show present research issues and research limitations, as well as suggest possible future antioxidant treatment strategies for patients with PBOO.

Improvement of Persistent Detrusor Overactivity through Treatment with a Phytotherapeutic Agent (WSY-1075) after Relief of Bladder Outlet Obstruction

Purpose

Many patients with benign prostatic hyperplasia need treatment for remaining storage symptoms after surgery. Therefore, we evaluated the effect of the phytotherapeutic agent WSY-1075 on persistent detrusor overactivity (DO) after the relief of bladder outlet obstruction (BOO).

Materials and Methods

Rats were assigned to 3 groups: control (n=6), persistent DO (n=6), and persistent DO treated with the phytotherapeutic agent WSY-1075 (n=6). Persistent DO after relief of partial BOO was generated in the rat model, and 6 of the rats with this condition were orally administered WSY-1075. After 4 weeks of administration, cystometry was performed. Additionally, 8-hydroxy-2-deoxyguanosine and superoxide dismutase were measured to evaluate oxidative stress in the bladder. Pro-inflammatory cytokines, such as interleukin-8 and tumor necrosis factor-α, were analyzed, as were the M2 and M3 muscarinic receptors of the bladder.

Results

Significantly increased contraction pressure and a decreased contraction interval were observed in the persistent DO group after relief of BOO. Moreover, oxidative stress, pro-inflammatory cytokines, and M3 muscarinic receptors were significantly increased. After treatment with WSY-1075, significantly reduced DO was observed by cystometry in comparison with the persistent DO group. Additionally, significantly decreased levels of oxidative stress, pro-inflammatory cytokines, and M3 muscarinic receptors in the bladder were observed after treatment with WSY-1075.

Conclusions

Treatment with WSY-1075 improved persistent DO after the relief of BOO mediated by antioxidative and anti-inflammatory effects. Further studies are necessary to identify the exact mechanism of the treatment effect of WSY-1075.

Pharmacological treatment of chronic pelvic ischemia

Epidemiological studies have shown that lower urinary tract symptoms, including overactive bladder, commonly occur in both men and women, with an age-related increase in both sexes. Vascular endothelial dysfunction and urological symptoms are common in the metabolic syndrome; they also occur during the human ageing process and are independent risk factors for the development of atherosclerosis and hypertension. Pelvic arterial insufficiency may lead to impaired lower urinary tract perfusion and play an important role in the development of bladder dysfunction such as detrusor overactivity and overactive bladder. It seems reasonable, but has not been definitely established clinically, that chronic ischemia-related bladder dysfunction will progress to bladder underactivity. Studies in experimental models in rabbits and rats have shown that pelvic arterial insufficiency may result in significant bladder ischemia with reduced bladder wall oxygen tension, oxidative stress, increased muscarinic receptor activity, ultrastructural damage, and neurodegeneration. Several types of drug may be able to prevent some of these changes. Even if the α1-adrenoceptor blocker, silodosin, the phosphodiesterase type 5 inhibitor, tadalafil, the β3-α1-adrenoceptor agonist, mirabegron, and the free radical scavenger, melatonin, were unable to prevent the development of neointimal hyperplasia and consequent luminal occlusion in animal models, they all exerted a protecting effect on urodynamic parameters, and on the functional and morphological changes of the bladder demonstrable in vitro. The different mechanisms of action of the drugs suggest that many factors are involved in the pathogenesis of chronic ischemia-induced bladder dysfunction and can be targets for intervention. Since several of the agents tested are used clinically and effectively for relieving lower urinary tract symptoms, the results from animal models of chronic bladder ischemia seem to have translational value. Animal models may be of relevance for designing clinical studies to demonstrate if a certain drug may prevent progression of ischemia-related functional and morphological bladder changes.

Bladder function in 17β-estradiol-induced nonbacterial prostatitis model in Wistar rat

OBJECTIVES

To investigate bladder function in a model of nonbacterial prostatitis (NBP) induced in castrated rats by 17β-estradiol injection.

METHODS

Ten-month-old male Wistar rats were divided into two groups, sham and NBP (both N = 8). NBP was induced by castration followed by daily subcutaneous injection of 17β-estradiol for 30 days. On the 31st day after surgery, we investigated (1) voiding behavior, (2) bladder blood flow (BBF), (3) prostate and bladder weight, and proinflammatory cytokines (TNF-α and CXCL1) levels and (4) bladder contractile responses to electrical field stimulation (EFS), carbachol and KCl.

RESULTS

(1) Voiding behavior (average micturition volume, total urine volume and number of micturitions) and (2) BBF were not significantly different between the sham and NBP groups. (3) NBP led to a significant decrease in prostatic weight and increase in proinflammatory cytokine levels in the prostate, but NBP did not cause a significant change in bladder weight or proinflammatory cytokine levels in the bladder. (4) Bladder contractile forces in response to EFS, carbachol and KCl were not significantly affected by NBP.

CONCLUSIONS

In this rat model, NBP did not cause a significant change in the level of proinflammatory cytokines in the bladder and affect bladder function.