Pathophysiological Studies of Overactive Bladder and Bladder Motor Dysfunction in a Rat Model of Metabolic Syndrome

Pathophysiology of Overactive Bladder and Pharmacologic Treatments Including β3-Adrenoceptor Agonists -Basic Research Perspectives

Overactive bladder (OAB) is a symptom-based syndrome defined by urinary urgency, frequency, and nocturia with or without urge incontinence. The causative pathology is diverse; including bladder outlet obstruction (BOO), bladder ischemia, aging, metabolic syndrome, psychological stress, affective disorder, urinary microbiome, localized and systemic inflammatory responses, etc. Several hypotheses have been suggested as mechanisms of OAB generation; among them, neurogenic, myogenic, and urothelial mechanisms are well-known hypotheses. Also, a series of local signals called autonomous myogenic contraction, micromotion, or afferent noises, which can occur during bladder filling, may be induced by the leak of acetylcholine (ACh) or urothelial release of adenosine triphosphate (ATP). They can be transmitted to the central nervous system through afferent fibers to trigger coordinated urgency-related detrusor contractions. Antimuscarinics, commonly known to induce smooth muscle relaxation by competitive blockage of muscarinic receptors in the parasympathetic postganglionic nerve, have a minimal effect on detrusor contraction within therapeutic doses. In fact, they have a predominant role in preventing signals in the afferent nerve transmission process. β3-adrenergic receptor (AR) agonists inhibit afferent signals by predominant inhibition of mechanosensitive Aδ-fibers in the normal bladder. However, in pathologic conditions such as spinal cord injury, it seems to inhibit capsaicin-sensitive C-fibers. Particularly, mirabegron, a β3-agonist, prevents ACh release in the BOO-induced detrusor overactivity model by parasympathetic prejunctional mechanisms. A recent study also revealed that vibegron may have 2 mechanisms of action: inhibition of ACh from cholinergic efferent nerves in the detrusor and afferent inhibition via urothelial β3-AR.

A positive association between the prevalence of circadian syndrome and overactive bladder in United States adults

Objective

To explore the association between the prevalence of circadian syndrome (CircS) and overactive bladder (OAB).

Materials and methods

Cross-section analysis was based on the National Health and Nutrition Examination Survey 2005-2018. Data regarding OAB was collected from questionnaires. The association between the prevalence of CircS and OAB was elucidated using three multivariable logistic regression models. Stratified and interaction analyses were performed to find whether some factors can modify the association.

Results

Totally 8,033 males and 8,065 females were included. People with CircS had a significantly higher prevalence of OAB compared to the non-CircS group in the fully-adjusted model (OR = 1.238, 95%CI 1.080-1.419). A significant positive correlation between the number of CircS components and the prevalence of OAB was observed when the components were ≥ 6 (OR = 1.975, 95%CI 1.463-2.665). No significant interaction was seen in the three models.

Conclusion

There is a positive association between the prevalence of CircS and OAB. When the number of components is ≥6, the prevalence of OAB shows a strongly positive correlation with the number of CircS components.

Effects of coconut oil long-term supplementation in Wistar rats during metabolic syndrome - regulation of metabolic conditions involving glucose homeostasis, inflammatory signals, and oxidative stress

This study was designed to evaluate the long-term effects of Fructose (20%) feeding in rats, simulating metabolic syndrome (MetS), and the effects of coconut oil (C.O.) supplementation when administered in a MetS context. MetS is a cluster of systemic conditions that represent an increased chance of developing cardiovascular diseases and type 2 diabetes in the future. C.O. has been the target of media speculation, and recent studies report inconsistent results. C.O. improved glucose homeostasis and reduced fat accumulation in Fructose-fed rats while decreasing the levels of triglycerides (TGs) in the liver. C.O. supplementation also increased TGs levels and fructosamine in serum during MetS, possibly due to white adipose tissue breakdown and high fructose feeding. Pro-inflammatory cytokines IL-1β and TNF-α were also increased in rats treated with Fructose and C.O. Oxidative stress marker nitrotyrosine is increased in fructose-fed animals, and C.O. treatment did not prevent this damage. No significant changes were observed in lipoperoxidation marker 4-Hydroxynonenal; however, fructose feeding increased total conjugated dienes and caused conjugated dienes to switch their conformation from cis-trans to trans-trans, which was not prevented by C.O. treatment. Potential benefits of C.O. have been reported with inconsistent results, and indeed we observed some benefits of C.O. supplementation in aiding weight loss, fat accumulation, and improving glucose homeostasis. Nonetheless, we also demonstrated that long-term C.O. supplementation could present some problematic effects with higher risk for individuals suffering MetS, including increased TGs and fructosamine levels and conformational changes in dienes.

Impaired insulin signaling at the bladder mucosa facilitates metabolic syndrome-associated bladder overactivity in rats with maternal and post-weaning fructose exposure

BACKGROUND/PURPOSE

Metabolic syndrome (MetS) and overactive bladder might share common pathophysiologies. Environmental fructose exposure during pre- and postnatal periods of rats may program MetS-associated bladder overactivity. We explored the dysregulated insulin signalling at bladder mucosa, as a common mechanism, in facilitating bladder overactivity in rats with MetS induced by maternal and post-weaning fructose diet.

METHODS

Male offspring of Sprague-Dawley rats were subject into 4 groups by maternal and post-weaning diets (i.e., Control/Control, Fructose/Control, Control/Fructose and Fructose/Fructose by diets). Micturition behavior was evaluated. Acidic ATP solution was used to elicit cystometric reflex along with insulin counteraction. Concentration-response curves to insulin were plotted. The canonical signalling pathway of insulin was evaluated in the bladder mucosal using Western blotting. Levels of detrusor cGMP and urinary NO₂ plus NO₃ were measured.

RESULTS

Male offspring with any fructose exposure presents traits of MetS and bladder overactivity. We observed all fructose exposure groups have the poor urodynamic response to insulin during ATP solution stimulation and poor insulin-activated detrusor relaxation in organ bath study. Compared to controls, the Control/Fructose and Fructose/Fructose groups showed the increased phosphorylation levels of IRS1 (Ser³⁰⁷) and IRS2 (Ser⁷³¹); thus, suppressed the downstream effectors and urinary NOx/detrusor cGMP levels. The Fructose/Control group showed the compensatory increase of phospho-AKT (Ser⁴⁷³) and phospho-eNOS/eNOS levels, but decreased in eNOS, phospho-eNOS, urinary NOx, and detrusor cGMP levels.

CONCLUSION

Our results show dysregulated insulin signalling at bladder mucosa should be a common mechanism of MetS-associated bladder overactivity programmed by pre-and postnatal fructose diet.

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.

Adipose-Derived Stem Cells and Their Derived Microvesicles Ameliorate Detrusor Overactivity Secondary to Bilateral Partial Iliac Arterial Occlusion-Induced Bladder Ischemia

(1) Background: We established a new bladder ischemia rat model through bilateral partial iliac arterial occlusion (BPAO) and investigated the therapeutic effect of adipose-derived stem cells (ADSCs) and ADSC-derived microvesicles (MVs); (2) Methods: The study included four groups: (1) sham, (2) BPAO, (3) BPAO + ADSCs, and (4) BPAO + ADSC-derived MVs. Female Wistar rats with BPAO were injected with ADSCs or ADSC-derived MVs through the femoral artery. Doppler flowmetry and real-time laser speckle contrast imaging were performed to quantify blood flow in the common iliac arteries and bladder microcirculation. A 24-h behavior study and transcystometrogram were conducted after 2 weeks. Bladder histology, immunostaining, and lipid peroxidation assay were performed. The expressions of P2X2, P2X3, M2, and M3 receptors and nerve growth factor (NGF) were evaluated; (3) Results: BPAO significantly reduced bladder microcirculation, intercontraction interval (ICI), and bladder volume and increased the amplitude of nonvoiding contraction, neutrophil infiltration, and malondialdehyde and NGF levels. ADSCs and ADSC-derived MVs significantly ameliorated these effects. The results of Western blot showed that the BPAO group exhibited the highest expression of M3 and P2X2 receptors. ADSCs significantly attenuated the expressions of M2 and P2X2 receptors. ADSC-derived MVs significantly attenuated the expressions of M3 and P2X2 receptors; (4) Conclusions: ADSCs and ADSC-derived MVs ameliorated the adverse effects of BPAO including bladder overactivity, bladder ischemia, and oxidative stress. Inflammation, muscarinic signaling, purinergic signaling, and NGF might be involved in the therapeutic mechanism.

Ketamine-induced urological toxicity: potential mechanisms and translation for adults with mood disorders receiving ketamine treatment

Intravenous (IV) ketamine has been shown to have rapid and robust antidepressant effects in adults with treatment-resistant depression (TRD). Urological toxicity has been observed in chronic ketamine abusers as evidenced by dysuria, urgency, and hematuria. The foregoing observation provides the basis for evaluating whether ketamine-induced urological toxicity (KIUT) is associated with sub-anesthetic doses of ketamine (0.5-1.0 mg/kg) in adults with mood disorders. The overarching objective of this article is to identify potential mechanisms of KIUT which appears to be dose and frequency dependent. Available research indicates that high-frequency ketamine is associated with disruption of the urothelial barrier as well as direct ketamine toxicity (i.e., decreased expression of junction proteins) in KIUT of the bladder. Chronic and high-frequency ketamine use is also associated with bladder inflammation mediated via neurogenic and IgE inflammation. Other non-mutually exclusive causes are nerve hyperplasia, hypersensitivity, cell apoptosis, microvascular damage, and overexpression of carcinogenic genes. Notwithstanding the evidence of KIUT in ketamine abusers, there is no evidence that ketamine and/or esketamine treatment in adults with mood disorders is associated with KIUT. However, all patients receiving ketamine/esketamine for mood disorder treatment should be queried about genitourinary symptoms during acute and, where applicable, maintenance dosing.

Fructose-induced metabolic disturbances in rats and its impact on stomach endocrine cell number and smooth muscle contractility

Context: Gastric ghrelin-positive endocrine cells (GHR + EC) were most dense in the oxyntic mucosa.Objective: We evaluated ECs and contractile activity in rat stomach with metabolic disorders.Materials and methods: Male Wistar rats were divided into two groups: Control (n = 9) received tap water and Fructose (n = 9) drank 15% fructose solution for 12 weeks. Streptozotocin was applied in a dose of 20 mg/kg b.w. two weeks after the beginning of the experiment on Fructose group. Smooth-muscle strips from the stomach were influenced by Angiotensin II for analysis of parameters of contractions. Stomach samples were elaborated with immunohistochemistry for ghrelin, somatostatin, gastrin antibodies and with double immunofluorescence.Results: In treated animals, GHR + EC were significantly increased in the corpus where somatostatin-positive cells were decreased. Contractile activity was decreased.Conclusions: The increase number of GHR + EC was discussed in the context of Somatostatin and Gastrin-positive ECs variations and correlated with the decrease of smooth muscle contraction.

Effect of a Carbohydrate-Rich Diet on Rat Detrusor Smooth Muscle Contractility: An Experimental Study

OBJECTIVES

We aimed to investigate the effect of a carbohydrate-rich diet on detrusor contractility in rats.

MATERIALS AND METHODS

Sprague-Dawley rats were randomized into two groups. The control group received regular food and water. The study group received carbohydrate-rich diet for six weeks. The rats' detrusor muscle was isolated for pharmacological and histopathological examinations.

RESULTS

In the control and study groups, mean body weights were 431.5 ± 27.6 g and 528.0 ± 36.2 g, respectively (p < 0.001). Electrical stimulation of the detrusor strips of the control group resulted in gradual contraction. A decreased contractile response was shown in the study group. Acetylcholine in 10-7-10-3 molar concentration produced a decreased contractile response in the study group, compared to the control group (p < 0.01). The study group showed marked subepithelial and intermuscular fibrosis in the bladder.

CONCLUSION

Carbohydrate-rich diet causes marked subepithelial and extracellular fibrosis and changes in contractility in the detrusor within a six-week period. Changes have higher costs in therapeutic choices and correction of these changes remains difficult. Putting an end to carbohydrate-rich diet would seem to be more cost-effective than dealing with the effects of consuming it in high proportions which should be the national policy worldwide.

Maternal Fructose Exposure Programs Metabolic Syndrome-Associated Bladder Overactivity in Young Adult Offspring

Maternal fructose exposure (MFE) programs the development of metabolic syndrome (MetS) in young adult offspring. Epidemiological data indicate that MetS may increase the risks of overactive bladder (OAB) symptoms. However, it remains unknown whether MFE programs MetS-associated bladder dysfunction in adult offspring. Using Sprague-Dawley rats, we investigated the effects of MFE during pregnancy and lactation on developmental programming of MetS-associated bladder dysfunction. In addition, next generation sequencing technology was used to identify potential transcripts involved in the programmed bladder dysfunction in adult male offspring to MFE. We found that MFE programmed the MetS-associated OAB symptoms (i.e., an increase in micturition frequency and a shortened mean inter-contractile interval) in young adult male offspring, alongside significant alterations in bladder transcripts, including Chrm2, Chrm3, P2rx1, Trpv4, and Vipr2 gene expression. At protein level, the expressions of M₂-, M₃-muscarinic and P2X₁ receptor proteins were upregulated in the MFE bladder. Functionally, the carbachol-induced detrusor contractility was reduced in the MFE offspring. These data suggest that alterations in the bladder transcripts and impairment of the bladder cholinergic pathways may underlie the pathophysiology of programmed bladder dysfunction in adult offspring to MFE.

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.

Incidence of Nitrituria and Its Association With Metabolic Syndrome: Results From the Korean National Health and Nutrition Examination Survey V (2010–2012)

Purpose:

To investigate the incidence of nitrituria and the relationship between nitrituria and metabolic syndrome (MetS).

Methods:

Data from the Korean National Health and Nutrition Examination Survey V were used. A total of 19,083 participants were included. The chi-square test, the Mantel-Haenszel extension, logistic regression analysis, and multiple linear regression were used to analyze the data.

Results:

A total of 2.0% of the participants had nitrituria. The incidence of nitrituria significantly increased with age (P trend<0.001). In addition, nitrituria in women began to significantly increase in the fifth decade, more than in men, and this difference was maintained in the 60s, 70s, and greater than 70s age groups (P<0.001). After adjusting for confounders, the odds ratio (OR) for nitrituria in the MetS group was significantly increased, as compared to the OR for nitrituria in the group without MetS (MetS: OR, 1.577; 95% confidence interval [CI], 1.134–2.192; P=0.007). The glycosylated hemoglobin of the nitrite positive group was significantly higher than the negative group (adjusted mean ±standard error: 6.108 ±0.081 vs. 5.883±0.065, P<0.001).

Conclusions:

An effective health policy for urinary tract infection (UTI) is needed for older age groups and women. Screening or management guidelines for UTI are needed in MetS patients.

Impaired Excitatory Neurotransmission in the Urinary Bladder from the Obese Zucker Rat: Role of Cannabinoid Receptors

Metabolic syndrome (MS) is a known risk factor for lower urinary tract symptoms. This study investigates whether functional and expression changes of cannabinoid CB₁ and CB₂ receptors are involved in the bladder dysfunction in an obese rat model with insulin resistance. Bladder samples from obese Zucker rat (OZR) and their respective controls lean Zucker rat (LZR) were processed for immunohistochemistry and western blot for studying the cannabinoid receptors expression. Detrusor smooth muscle (DSM) strips from LZR and OZR were also mounted in myographs for isometric force recordings. Neuronal and smooth muscle CB₁ and CB₂ receptor expression and the nerve fiber density was diminished in the OZR bladder. Electrical field stimulation (EFS) and acetylcholine (ACh) induced frequency- and concentration-dependent contractions of LZR and OZR DSM. ACh contractile responses were similar in LZR and OZR. EFS-elicited contractions, however, were reduced in OZR bladder. Cannabinoid receptor agonists and antagonists failed to modify the DSM basal tension in LZR and OZR In LZR bladder, EFS responses were inhibited by ACEA and SER-601, CB₁ and CB₂ receptor agonists, respectively, these effects being reversed by ACEA plus the CB₁ antagonist, AM-251 or SER-601 plus the CB₂ antagonist, AM-630. In OZR bladder, the inhibitory action of ACEA on nerve-evoked contractions was diminished, whereas that SER-601 did not change EFS responses. These results suggest that a diminished function and expression of neuronal cannabinoid CB₁ and CB₂ receptors, as well as a lower nerve fiber density is involved in the impaired excitatory neurotransmission of the urinary bladder from the OZR.

Estimating postvoid residual volume without measuring residual bladder volume during serial cystometrograms

The postvoid residual volume (PVR) is a common urodynamic parameter used to quantify the severity of lower urinary tract dysfunction. However, the serial cystometrograms that are typically used to assess bladder function in animal models make measuring PVR very difficult. Current approaches are to either remove PVR after each void to measure it, which is disruptive to the bladder, or to neglect the unknown contribution to PVR from ureter flow, which results in inaccurate estimates. We propose a procedure to estimate PVR during a serial cystometrogram that requires only a single measurement, rather than measuring after each void. Moreover, this measurement can occur at the end of the experiment such that it does not affect the bladder during data collection. We mathematically express PVR for all voids during a serial cystometrogram using a linear recurrence equation and use this equation to build an estimation procedure for PVR. Using in vivo measurements in urethane anesthetized rats and computer simulations we show that the estimation procedure is at least as accurate in determining PVR as the traditional method of measuring PVR after each void. Furthermore, we demonstrate the adverse effects of repeated PVR measurements in a common animal model of cystitis. Using the proposed procedure can increase the efficiency and accuracy of determining PVR for a serial cystometrogram and is less disruptive to the system under study. This, in turn, allows the calculation of other urodynamic parameters that are critical for research studies, including voiding efficiency and bladder capacity.

Structural and functional changes in gap junctional intercellular communication in a rat model of overactive bladder syndrome induced by partial bladder outlet obstruction

The aim of the present study was to investigate the association between connexin (Cx)43 levels and alterations in gap junctional mediation of intercellular communication in overactive bladder syndrome (OAB), and to examine the effects of connexin inhibitor on this condition. Adult female Wistar rats with OAB following partial bladder outlet obstruction (PBBO) (OAB group, n=37) and sham-operated rats (control group, n=17) were studied. The ultrastructure of the rat detrusor was observed by transmission electron microscopy and the protein expression levels of Cx43 were analyzed using western blot analysis. Furthermore, bladder detrusor cells in both groups were cultured and cells in the OAB group were randomly divided into ten groups. In nine of these groups, 18-β glycyrrhetinic acid (18β-GA) was administered at various doses and durations. All groups were compared using fluorescence redistribution after photobleaching and a laser scanning confocal microscope. Cystometry demonstrated that gap junctions were an abundant mechanism among adjacent cells, and Cx43 protein expression levels were increased in the OAB group following 6 weeks of obstruction, as compared with the control group. Mean fluorescence recovery rates in the OAB group were significantly increased, as compared with the control group (P<0.01). Mean fluorescence recovery rates were noted following 18β-GA administration. These results suggested that upregulation of Cx43 induces structural and functional alterations in gap junctional intercellular communication following PBOO, and connexin inhibitors may be a novel therapeutic strategy for the clinical treatment of OAB.

Ketamine-induced ulcerative cystitis and bladder apoptosis involve oxidative stress mediated by mitochondria and the endoplasmic reticulum

Ketamine abusers develop severe lower urinary tract symptoms. The major aims of the present study were to elucidate ketamine-induced ulcerative cystitis and bladder apoptosis in association with oxidative stress mediated by mitochondria and the endoplasmic reticulum (ER). Sprague-Dawley rats were distributed into three different groups, which received normal saline or ketamine for a period of 14 or 28 days, respectively. Double-labeled immunofluorescence experiments were performed to investigate tight junction proteins for urothelial barrier functions. A TUNEL assay was performed to evaluate the distribution of apoptotic cells. Western blot analysis was carried out to examine the expressions of urothelial tight junction proteins, ER stress markers, and apoptosis-associated proteins. Antioxidant enzymes, including SOD and catalase, were investigated by real-time PCR and immunofluorescence experiments. Ketamine-treated rats were found to display bladder hyperactivity. This bladder dysfunction was accompanied by disruptions of epithelial cadherin- and tight junction-associated proteins as well as increases in the expressions of apoptosis-associated proteins, which displayed features of mitochondria-dependent apoptotic signals and ER stress markers. Meanwhile, expressions of mitochondria respiratory subunit enzymes were significantly increased in ketamine-treated bladders. Conversely, mRNA expressions of the antioxidant enzymes Mn-SOD (SOD2), Cu/Zn-SOD (SOD1), and catalase were decreased after 28 days of ketamine treatment. These results demonstrate that ketamine enhanced the generation of oxidative stress mediated by mitochondria- and ER-dependent pathways and consequently contributed to bladder apoptosis and urothelial lining defects. Such oxidative stress-enhanced bladder cell apoptosis and urothelial barrier defects are potential factors that may play a crucial role in bladder overactivity and ulceration.

Possible pathophysiology of ketamine-related cystitis and associated treatment strategies

Ketamine-related cystitis is characterized by ketamine-induced urinary frequency and bladder pain. It has become a serious problem in recent years. The most typical grossly pathological bladder change with ketamine related cystitis is a contracted bladder and bladder wall thickening. Ulcerative cystitis with an easily bleeding mucosa is a common cystoscopic finding. Microscopically, the urothelium is denuded and is infiltrated by inflammatory cells, such as mast cells and eosinophils. The pathogenesis of ketamine-related cystitis is complicated and involves many different pathways. Past evidence suggests a direct toxic effect, bladder barrier dysfunction, neurogenic inflammation, immunoglobulin-E-mediated inflammation, overexpression of carcinogenic genes, abnormal apoptosis and nitric oxide synthase-mediated inflammation contribute to the pathogenesis of ketamine-related cystitis. The first step to managing ketamine-related cystitis is always asking patients to cease ketamine. Medical treatment might be helpful in patients with early ketamine-related cystitis and abstinence from ketamine. Several case studies showed that the intravesical installation of hyaluronic acid and intravesical injection of botulinum toxin type A were effective for symptom relief in selected patients. For patients with irreversible pathological change, such as contracted bladder, augmentation enterocystoplasty might be the only solution to increase bladder capacity and relieve intractable bladder pain.

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.

Molecular fingerprint of high fat diet induced urinary bladder metabolic dysfunction in a rat model

AIMS/HYPOTHESIS

Diabetic voiding dysfunction has been reported in epidemiological dimension of individuals with diabetes mellitus. Animal models might provide new insights into the molecular mechanisms of this dysfunction to facilitate early diagnosis and to identify new drug targets for therapeutic interventions.

METHODS

Thirty male Sprague-Dawley rats received either chow or high-fat diet for eleven weeks. Proteomic alterations were comparatively monitored in both groups to discover a molecular fingerprinting of the urinary bladder remodelling/dysfunction. Results were validated by ELISA, Western blotting and immunohistology.

RESULTS

In the proteome analysis 383 proteins were identified and canonical pathway analysis revealed a significant up-regulation of acute phase reaction, hypoxia, glycolysis, β-oxidation, and proteins related to mitochondrial dysfunction in high-fat diet rats. In contrast, calcium signalling, cytoskeletal proteins, calpain, 14-3-3η and eNOS signalling were down-regulated in this group. Interestingly, we found increased ubiquitin proteasome activity in the high-fat diet group that might explain the significant down-regulation of eNOS, 14-3-3η and calpain.

CONCLUSIONS/INTERPRETATION

Thus, high-fat diet is sufficient to induce significant remodelling of the urinary bladder and alterations of the molecular fingerprint. Our findings give new insights into obesity related bladder dysfunction and identified proteins that may indicate novel pathophysiological mechanisms and therefore constitute new drug targets.

[Urinary disorders and metabolic syndrome: prospective study]

OBJECTIVE

Metabolic syndrome (MS) risk factors are potentially implicated in the development of lower urinary tract symptoms (LUTS). The goals of this study were to analyze the prevalence of the LUTS in patients presenting with MS and to evaluate the correlation between the MS components and LUTS.

METHODS

A prospective study was conducted on a group of 34 patients with MS according to the criteria of the NCEP ATP III. Urinary symptom profile (USP) questionnaire was used to evaluate LUTS. The physical examination included: weight, waist circumference, body mass index (BMI) and blood pressure looking for orthostatic hypotension. The following laboratory data were obtained: fasting blood sugar, postprandial glycemia, glycosylated hemoglobin (HbA1c), HDL-cholesterol, LDL-cholesterol, triglycerides and total cholesterol.

RESULTS

The mean age was 56.2 years (±9.2). Twenty of the patients (58.8%) were females. All patients underwent diabetic and hypertension therapy. The mean BMI was 30.2±4.8 and waist circumference was 107.8±9.3 cm. USP total score was 8.3±6. Besides, 29 (85.2%) patients had overactive bladder symptom, and 13 (38.2%) patients presented with urinary stress incontinence. The overactive bladder USP score was significantly correlated with age, waist circumference, BMI and postprandial glycemia. The other parameters of MS were not correlated with urinary symptoms.

CONCLUSION

The most frequent urinary symptom in the MS was overactive bladder symptoms and urinary incontinence. The components of MS that influenced the USP score were abdominal obesity and hyperglycemia. The hypothesis of a link between MS and overactive bladder in diabetic patients with MS is plausible.

Insulin relaxes bladder via PI3K/AKT/eNOS pathway activation in mucosa: unfolded protein response-dependent insulin resistance as a cause of obesity-associated overactive bladder

We aimed to investigate the role of insulin in the bladder and its relevance for the development of overactive bladder (OAB) in insulin-resistant obese mice. Bladders from male individuals who were involved in multiple organ donations were used. C57BL6/J mice were fed with a high-fat diet for 10 weeks to induce insulin-resistant obesity. Concentration-response curves to insulin were performed in human and mouse isolated mucosa-intact and mucosa-denuded bladders. Cystometric study was performed in terminally anaesthetized mice. Western blot was performed in bladders to detect phosphorylated endothelial NO synthase (eNOS) (Ser1177) and the phosphorylated protein kinase AKT (Ser473), as well as the unfolded protein response (UPR) markers TRIB3, CHOP and ATF4. Insulin (1-100 nm) produced concentration-dependent mouse and human bladder relaxations that were markedly reduced by mucosal removal or inhibition of the PI3K/AKT/eNOS pathway. In mouse bladders, insulin produced a 3.0-fold increase in cGMP levels (P < 0.05) that was prevented by PI3K/AKT/eNOS pathway inhibition. Phosphoinositide 3-kinase (PI3K) inhibition abolished insulin-induced phosphorylation of AKT and eNOS in bladder mucosa. Obese mice showed greater voiding frequency and non-voiding contractions, indicating overactive detrusor smooth muscle. Insulin failed to relax the bladder or to increase cGMP in the obese group. Insulin-stimulated AKT and eNOS phosphorylation in mucosa was also impaired in obese mice. The UPR markers TRIB3, CHOP and ATF4 were increased in the mucosa of obese mice. The UPR inhibitor 4-phenyl butyric acid normalized all the functional and molecular parameters in obese mice. Our data show that insulin relaxes human and mouse bladder via activation of the PI3K/AKT/eNOS pathway in the bladder mucosa. Endoplasmic reticulum stress-dependent insulin resistance in bladder contributes to OAB in obese mice.

Effects of supraphysiological testosterone treatment and orchiectomy on ischemia/reperfusion-induced bladder dysfunction in male rabbits

INTRODUCTION

The roles of testosterone and orchiectomy on male bladder subjected to ischemic/reperfusion (I/R) injuries received little attention. To fill this gap, the present study intended to examine testosterone and orchiectomy effects on male rabbits subjected to I/R damages.

AIM

To elucidate the effects of testosterone and orchiectomy on contractile response, bladder morphology, interstitial fibrosis, and oxidative stress in male rabbit bladder subjected to I/R surgery.

METHODS

Male New Zealand rabbits were distributed into five groups as follows: Group 1 received sham surgical procedure. In group 2, I/R surgery was performed. In group 3, testosterone (100 μg/kg/day) was intramuscularly injected prior to I/R surgery. In group 4, orchiectomy was performed prior to I/R surgery. In group 5, orchiectomy was performed with subsequent testosterone administration, followed by I/R surgery. All the rabbits were euthanized 7 days after I/R. Comparative studies were analyzed to elucidate the effects of testosterone and orchiectomy on bladder dysfunction subjected to I/R injuries.

MAIN OUTCOME MEASURES

Bladder contractile function was evaluated. Masson's trichrome staining and immunohistochemical studies were performed to evaluate bladder morphology and intramural nerve terminals. Western blotting was examined to investigate the expressions of fibrosis and oxidative stress markers.

RESULTS

I/R surgery significantly decreased bladder contractility in response to various stimulations with and without testosterone treatment. I/R damages decreased bladder nerve density with and without testosterone. The expressions of fibrosis and oxidative stress-related proteins were increased by I/R injuries with or without testosterone treatment. Testosterone depletion significantly decreased the expressions of transforming growth factor-β and fibronectin expressions after I/R injury. Supraphysiological testosterone treatment after orchiectomy greatly increased the expressions of these fibrosis proteins; however, orchiectomy alone ameliorated I/R injuries.

CONCLUSIONS

Testosterone treatment or orchiectomy affected I/R-induced bladder damages in male rabbits. Orchiectomy decreased the level of fibrosis and oxidative stress markers and increased neurofilament densities. Supraphysiological exogenous testosterone administration after orchiectomy further exacerbated such detrimental effects of I/R.

Improvement of erectile function by Korean red ginseng (Panax ginseng) in a male rat model of metabolic syndrome

The seriousness of metabolic syndrome is not due to the disease itself but its promotion of other diseases, such as erectile dysfunction and cardiovascular and cerebrovascular diseases. We investigated the effects of Korean red ginseng (KRG, Panax ginseng) extract on erectile function in a rat model of metabolic syndrome. We divided the rats into three groups: control, metabolic syndrome+normal saline (N/S) and metabolic syndrome+KRG. To determine the occurrence of metabolic syndrome in all groups, body weight and various biochemical parameters (e.g., blood glucose, insulin, cholesterol) were measured, and the intra-abdominal glucose tolerance test was performed. To investigate penile erection, the peak intracavernosal pressure (ICP), mean arterial pressure (MAP) and Masson's trichrome stain were evaluated. Erectile function was also investigated by measuring the cyclic guanosine monophosphate (cGMP) levels of the corpus cavernosum. We found that the various biochemical parameters and body weight were similar in the metabolic syndrome+KRG group and the control group, although the values were slightly higher. The peak ICP/MAP ratio of the metabolic syndrome+N/S group was markedly decreased compared to the other groups. The cGMP level of the corpus cavernosum in the metabolic syndrome+N/S group was significantly lower than that of the other groups. As demonstrated in this model of metabolic syndrome with erectile dysfunction, KRG may improve erectile function.

Alterations in peripheral purinergic and muscarinic signaling of rat bladder after long-term fructose-induced metabolic syndrome

PURPOSE

We explored the pathophysiologic mechanisms of long-term fructose-induced lower urinary tract symptoms (LUTS) in rats.

METHODS

Male Wistar rats were fed with fructose for 3 or 6 months. Biochemical and transcystometric parameters were compared between fructose-fed and age-matched normal-diet rats. Pelvic nerve and external urethral sphincter-electromyogram activity recordings were performed to investigate fructose effects on neural control of bladders. Mitochondrial structure, ATP and acetylcholine content and purinergic and muscarinic cholinergic receptors were examined. Cytosolic cytochrome C staining by Western blot and immunocytochemistry for mitochondrial injury and PGP 9.5 stain for nerve density were also determined.

RESULTS

The fructose-fed rats with higher plasma triglyceride, LDL and fasting glucose levels displayed LUTS with increased frequency and suppressed voiding contractile amplitude in phase 1 and phase 2 duration versus normal-diet control. Fructose feeding altered the firing types in pelvic afferent and efferent nerves and external urethral sphincter-electromyogram activity. Increased mast cell number, disrupted and swollen mitochondria, increased cytosolic cytochrome C stain and expression and decreased nerve density in bladder smooth muscle layers appeared in the fructose-fed rats. Fructose feeding also significantly reduced ATP and acetylcholine content and enhanced protein expression of postsynaptic P(2)X(1), P(2)X(2) and P(2)X(3) purinergic receptors and M(2) and M(3) muscarinic cholinergic receptors expression in the smooth muscles of urinary bladder.

CONCLUSION

Long-term fructose feeding induced neuropathy and myopathy in the urinary bladders. Impaired mitochondrial integrity, reduced nerve density, ATP and acetylcholine content and upregulation of purinergic and muscarinic cholinergic receptors expression may contribute to the bladder dysfunction of fructose-fed animals.

Sensory dysfunction of bladder mucosa and bladder oversensitivity in a rat model of metabolic syndrome

Purpose

To study the role of sensory dysfunction of bladder mucosa in bladder oversensitivity of rats with metabolic syndrome.

Materials and Methods

Female Wistar rats were fed a fructose-rich diet (60%) or a normal diet for 3 months. Based on cystometry, the fructose-fed rats (FFRs) were divided into a group with normal detrusor function or detrusor overactivity (DO). Acidic adenosine triphosphate (ATP) solution (5mM, pH 3.3) was used to elicit reflex micturition. Cystometric parameters were evaluated before and after drug administration. Functional proteins of the bladder mucosa were assessed by western blotting.

Results

Compared to the controls, intravesical acidic ATP solution instillation induced a significant increase in provoked phasic contractions in both FFR groups and a significant decrease in the mean functional bladder capacity of group DO. Pretreatment with capsaicin for C-fiber desentization, intravesical liposome for mucosal protection, or intravenous pyridoxal 5-phosphate 6-azophenyl-2′,4′-disulfonic acid for antagonized purinergic receptors can interfere with the urodynamic effects of intravesical ATP in FFRs and controls. Over-expression of TRPV1, P2X₃, and iNOS proteins, and down-regulation of eNOS proteins were observed in the bladder mucosa of both fructose-fed groups.

Conclusions

Alterations of sensory receptors and enzymes in the bladder mucosa, including over-expression of TRPV1, P2X₃, and iNOS proteins, can precipitate the emergence of bladder phasic contractions and oversensitivity through the activation of C-afferents during acidic ATP solution stimulation in FFRs. The down-regulation of eNOS protein in the bladder mucosa of FFRs may lead to a failure to suppress bladder oversensitivity and phasic contractions. Sensory dysfunction of bladder mucosa and DO causing by metabolic syndrome are easier to elicit bladder oversensitivity to certain urothelium stimuli.