Oxidative stress status accompanying diabetic bladder cystopathy results in the activation of protein degradation pathways

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.

Potential role of oxidative stress in the pathogenesis of diabetic bladder dysfunction

Diabetes mellitus is a chronic metabolic disease, posing a considerable threat to global public health. Treating systemic comorbidities has been one of the greatest clinical challenges in the management of diabetes. Diabetic bladder dysfunction, characterized by detrusor overactivity during the early stage of the disease and detrusor underactivity during the late stage, is a common urological complication of diabetes. Oxidative stress is thought to trigger hyperglycaemia-dependent tissue damage in multiple organs; thus, a growing body of literature has suggested a possible link between functional changes in urothelium, muscle and the corresponding innervations. Improved understanding of the mechanisms of oxidative stress could lead to the development of novel therapeutics to restore the redox equilibrium and scavenge excessive free radicals to normalize bladder function in patients with diabetes.

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.

Astragaloside IV Protects Detrusor from Partial Bladder Outlet Obstruction-Induced Oxidative Stress by Activating Mitophagy through AMPK-ULK1 Pathway

Aims

Bladder outlet obstruction (BOO) and the consequent low contractility of detrusor are the leading causes of voiding dysfunction. In this study, we aimed to evaluate the pharmacological activity of astragaloside IV (AS-IV), an antioxidant biomolecule that possess beneficial effect in many organs, on detrusor contractility and bladder wall remodeling process.

Methods

Partial BOO (pBOO) was created by urethral occlusion in female rats, followed by oral gavage of different dose of AS-IV or vehicle. Cystometric evaluation and contractility test were performed. Bladder wall sections were used in morphology staining, and bladder tissue lysate was used for ELISA assay. Primary smooth muscle cells (SMCs) derived from detrusor were used for mechanism studies.

Results

Seven weeks after pBOO, the bladder compensatory enlarged, and the contractility in response to electrical or chemical stimuli was reduced, while AS-IV treatment reversed this effect dose-dependently. AS-IV also showed beneficial effect on reversing the bladder wall remodeling process, as well as reducing ROS level. In mechanism study, AS-IV activated mitophagy and alleviated oxidative stress via an AMPK-dependent pathway.

Conclusion

Out data suggested that AS-IV enhanced the contractility of detrusor and protected the bladder from obstruction induced damage, via enhancing the mitophagy and restoring mitochondria function trough an AMPK-dependent way.

Oxidative Stress: A Putative Link Between Lower Urinary Tract Symptoms and Aging and Major Chronic Diseases

Aging and major chronic diseases are risk factors for lower urinary tract symptoms (LUTS). On the other hand, oxidative stress (OS) is one of the fundamental mechanisms of aging and the development of chronic diseases. Therefore, OS might be a candidate mechanism linking these two clinical entities. This article aims to summarize the studies on the prevalence of LUTS, the role of OS in aging and chronic diseases, and the potential mechanisms supporting the putative link. A comprehensive literature search was performed to identify recent reports investigating LUTS and OS in major chronic diseases. In addition, studies on the impact of OS on the lower urinary tract, including bladder, urethra, and prostate, were collected and summarized. Many studies showed LUTS are prevalent in aging and major chronic diseases, including obesity, metabolic syndrome, diabetes, cardiovascular disease, hypertension, obstructive sleep apnea, autoimmune diseases, Alzheimer’s disease, and Parkinson’s disease. At the same time, OS is a key component in the pathogenesis of those chronic diseases and conditions. Recent studies also provided evidence that exacerbated OS can cause functional and/or structural changes in the bladder, urethra, and prostate, leading to LUTS. The reviewed data support the concept that OS is involved in multiple risk factors-associated LUTS, although further studies are needed to confirm the causative relationship. The specific ROS/RNS and corresponding reactions/pathways involved in chronic diseases and associated LUTS should be identified in the future and could serve as therapeutic targets.

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

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

50 week ultrasound imaging and ultrastructural abnormalities of bladder after sugar diuresis and diabetes mellitus in rats

PURPOSE

To investigate 50 week ultrasound imaging and ultrastructure changes of bladder in diuresis and diabetes rats.

METHODS

Forty-two healthy male Sprague-Dawley rats were randomly divided into control group, sugar-induced diuresis group and streptozotocin-induced diabetes group. The 24 h drinking and urine volume were calculated from 21 to 31 weeks. Using ultrasound to assess bladders after 49 weeks. Bladders were examined by transmission electron microscope after 50 weeks.

RESULTS

The drinking and urine volume significantly increased in the diuresis and diabetes groups. The bladder morphology and bladder wall thickness increased in the diuresis and diabetes groups. Bladder stones, bladder overdistension and urinary retention were seen in the diuresis and diabetes groups. Urothelium manifested degeneration, denudation and necrosis in the diuresis and diabetes groups. The mitochondrial vacuolar degeneration in the urothelial cells was seen in the diabetes group. The subepithelial vascular endothelial cells hyperplasia with a narrowed lumen were observed in the diabetes group. Abnormal mitochondria were rarely seen in the control group. The mitochondrial vacuolar degeneration in the detrusor was more severe in the diabetes group than in the diuresis group. The detrusor muscle and axon degeneration were observed in the diuresis and diabetes groups. Two rats in the diuresis group share similarities with diabetes group (2/6).

CONCLUSION

Long-term diabetes mellitus can cause increments of urinary bladder morphology and bladder wall thickness, urinary retention and bladder stones. Ultrastructural degeneration of the bladder might be the morphological bases of diabetic cystopathy.

Autonomic neuropathy and urologic complications in diabetes

Diabetic autonomic neuropathy affects the entire autonomic nervous system and can lead to dysfunction of the cardiovascular, gastrointestinal, and genitourinary organ systems. Genitourinary dysfunction associated with diabetic autonomic neuropathy includes diabetic bladder dysfunction, sexual dysfunction, and recurrent urinary tract infections. Urological complications in diabetes mellitus are very common; in fact, genitourinary complications are more common than diabetic neuropathy or nephropathy. While several studies have reported on genitourinary dysfunction in individuals with diabetes, UroEDIC, an ancillary study to the Diabetes Control and Complications Trial (DCCT) and its observational follow up, the Epidemiology of Diabetes Interventions and Complications study (EDIC), comprehensively characterized the association between urologic complications and cardiovascular autonomic neuropathy. UroEDIC demonstrated significant associations between autonomic neuropathy and urologic complications in type 1 diabetes, specifically erectile dysfunction, female sexual dysfunction, and lower urinary tract symptoms. In this narrative review, we review the current literature on urological complications in diabetes.

CGRP Reduces Apoptosis of DRG Cells Induced by High-Glucose Oxidative Stress Injury through PI3K/AKT Induction of Heme Oxygenase-1 and Nrf-2 Expression

Dorsal root ganglion (DRG) neurons, which are sensitive to oxidative stress due to their anatomical and structural characteristics, play a complex role in the initiation and progression of diabetic bladder neuropathy. We investigated the hypothesis that the antioxidant and antiapoptotic effects of CGRP may be partly related to the expression of Nrf2 and HO-1, via the phosphatidylinositol 3-kinase (PI3K)/AKT pathway, thus reducing apoptosis and oxidative stress responses. This study shows that CGRP activates the PI3K/AKT pathway, thereby inducing increased expression of Nrf2 and HO-1 and resulting in the decrease of reactive oxygen species and malondialdehyde levels and reduced neuronal apoptosis. These effects were suppressed by LY294002, an inhibitor of the PI3K/AKT pathway. Therefore, regulation of Nrf2 and HO-1 expression by the PI3K/AKT pathway plays an important role in the regulation of the antioxidant and antiapoptotic responses in DRG cells in a high-glucose culture model.

Urodynamic analysis of the impact of diabetes mellitus on bladder function

OBJECTIVES

To analyze sequential changes of diabetic cystopathy based on urodynamic data in patients with diabetes mellitus.

METHODS

Participants included male diabetes patients who underwent a pressure flow study at Nagoya University Graduate School of Medicine, Nagoya, Japan, from April 2005 to October 2016. Patients with a previous history of lower urinary tract dysfunction were excluded. Bladder dysfunction was categorized into four urodynamic patterns: (i) normal; (ii) detrusor overactivity with normal detrusor contractility; (iii) detrusor hyperreflexia/impaired contractility; and (iv) detrusor underactivity. The urodynamic patterns were evaluated according to the presence of diabetic retinopathy and nephropathy, which was correlated to diabetes mellitus duration. Furthermore, the association of clinical factors with voiding function, as well as sensory function, was investigated.

RESULTS

A total of 57 patients were enrolled. Detrusor overactivity with normal detrusor contractility patterns was seen only in cases with neither diabetic retinopathy nor diabetic nephropathy, whereas the prevalence of detrusor hyperreflexia/impaired contractility pattern was highest in cases with diabetic retinopathy. Detrusor underactivity pattern was found with the highest frequency in cases with both diabetic retinopathy and diabetic nephropathy. On multivariate analysis, the existence of diabetic retinopathy was only significantly correlated with bladder contractility index. Furthermore, multivariate analysis showed that first desire volume and maximum cystometric capacity were significantly positively correlated with post-void residual urine volume, and also negatively correlated with voiding efficiency independent of bladder contractility index.

CONCLUSIONS

Diabetes patients have diverse progressive bladder dysfunction according to the diabetes stage. An optimal screening program is necessary to detect and manage diabetic cystopathy at an early stage.

Urothelial Senescence in the Pathophysiology of Diabetic Bladder Dysfunction-A Novel Hypothesis

Diabetic bladder dysfunction (DBD) is a well-recognized and common symptom affecting up to 50% of all diabetic patients. DBD has a broad range of clinical presentations ranging from overactive to underactive bladder symptoms that develops in middle-aged to elderly patients with long standing and poorly controlled diabetes. Low efficacy of current therapeutics and lifestyle interventions combined with high national healthcare costs highlight the need for more research into bladder dysfunction pathophysiology and novel treatment options. Cellular senescence is an age-related physiologic process in which cells undergo irreversible growth arrest induced by replicative exhaustion and damaging insults. While controlled senescence negatively regulates cell proliferation and promotes tissue regeneration, uncontrolled senescence is known to result in tissue dysfunction through enhanced secretion of inflammatory factors. This review presents previous scientific findings and current hypotheses that characterize diabetic bladder dysfunction. Further, we propose the novel hypothesis that cellular senescence within the urothelial layer of the bladder contributes to the pro-inflammatory/pro-oxidant environment and symptoms of diabetic bladder dysfunction. Our results show increased cellular senescence in the urothelial layer of the bladder; however, whether this phenomenon is the cause or effect of DBD is unknown. The urothelial layer of the bladder is made up of transitional epithelia specialized to contract and expand with demand and plays an active role in transmission by modulating afferent activity. Transition from normal functioning urothelial cells to secretory senescence cells would not only disrupt the barrier function of this layer but may result in altered signaling and sensation of bladder fullness; dysfunction of this layer is known to result in symptoms of frequency and urgency. Future DBD therapeutics may benefit from targeting and preventing early transition of urothelial cells to senescent cells.

Improvement in bladder dysfunction after bladder transplantation of amniotic fluid stem cells in diabetic rats

To examine the effects of human amniotic fluid stem cells (hAFSCs) transplantation on bladder function and molecular changes in diabetic rats, 60 female Sprague-Dawley rats were used for study. Three groups were assigned including sham control rats, streptozotocin (STZ, 60 mg/kg)-induced diabetic rats and STZ-induced diabetic rats plus bladder hAFSCs transplantation. Compared to controls, diabetic rats had decreased body weight but increased bladder weight. Cystometries showed non-voiding contraction, residual volume, voided volume and intercontraction interval increased significantly in diabetic rats at week 4 and 12 after DM induction, but improved after hAFSCs transplantation. The immunoreactivities and mRNAs of nerve growth factor (NGF) decreased significantly in diabetic bladder at week 4 and 12 after DM induction, but recovered after hAFSCs transplantation. The immunoreactivities and mRNAs of M2 and M3 muscarinic receptor increased significantly in diabetic bladder at week 4 after DM induction but recovered after hAFSCs transplantation. The immunoreactivity of 8-hydroxy-20-deoxyguanosine increased significantly in diabetic bladder at week 4 and 12 after DM induction but reduced after hAFSCs transplantation. The present study showed bladder dysfunction in STZ-induced diabetic rats could be improved by hAFSCs transplantation into bladder, which may be related to the recovery of bladder NGF and muscarinic receptors.

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.

Endoplasmic reticulum stress is involved in apoptosis of detrusor muscle in streptozocin-induced diabetic rats

AIMS

Endoplasmic reticulum stress (ERS) has been proven to be associated with apoptosis and plays a critical role in the development of many diabetic complications. In the pathogenesis of diabetic cystopathy (DCP), the role of ERS is still unclear. Our study is aimed at the investigation of the involvement of ERS-associated detrusor muscle apoptosis in streptozocin (STZ)-induced diabetic rats.

METHODS

At different timepoints (4, 8, 12, and 16 weeks after induction of type 1 diabetic rat models), hematoxylin & eosin (H&E) staining was performed to assess the histological changes of the diabetic detrusor; the sub-cellular ultrastructure, especially the zone of endoplasmic reticulum (ER), was observed by transmission electron microscopy (TEM), and the terminal deoxynucleotidyl transferase-mediated DNA nick-end labeling (TUNEL) staining was used to identify the enhanced apoptosis. Moreover, the expression of three hallmarks of ERS-associated apoptosis, including glucose-regulated protein 78 (GRP78), CCAAT/enhancer-binding protein homologous protein (CHOP), and caspase12, was detected by quantitative real-time polymerase chain reaction (qRT-PCR) and Western blot.

RESULTS

Light microscopic impairments of histology, including progressive loosely packed muscle bundles and increased fibrous tissue, can be seen; the ultrastructural changes featuring the swollen and fused cisternaes in ER zone and deformed nucleus were also observed in the detrusor smooth muscle (DSM). Increased apoptosis and elevated expression of GRP78, CHOP, and caspase12 at both protein and mRNA levels in a time-dependent fashion were detected.

CONCLUSIONS

The occurrence of ERS-associated apoptosis may be involved in the development of DCP and may contribute to the diabetic detrusor impairment. Neurourol. Urodynam. 36:65-72, 2017. © 2015 Wiley Periodicals, Inc.

Effects of Moderate Alcohol Intake in the Bladder of the Otsuka Long Evans Tokushima Fatty Diabetic Rats

Diabetes is related with a number of cystopathic complications. However, there have been no studies about the influence of alcohol consumption in the bladder of type 2 diabetes. Thus, we investigated the effect of moderate alcohol intake in the bladder of the Otsuka Long Evans Tokushima Fatty (OLETF) diabetic rat. The non-diabetic Long-Evans Tokushima Otsuka (LETO, n=14) and the OLETF control group (n=14) were fed an isocaloric diet; the LETO (n=14) and the OLETF ethanol group (n=14) were fed 36% ethanol 7 g/kg/day. After ten weeks, muscarinic receptors, RhoGEFs, myogenic change, and the level of oxidative stress were evaluated. Moderate alcohol intake significantly decreased excessive muscarinic receptor and Rho kinase expressions in the OLETF rats compared with the LETO rats. In addition, iNOS and collagen expression were not changed in the OLETF rats in spite of alcohol consumption. Superoxide dismutase levels, which is involved in antioxidant defense, in the LETO rats were significantly decreased after alcohol consumption, however those in the OLETF rats were similar. Moderate alcohol consumption reduces the oxidative stress, and may prevent molecular and pathologic changes of the bladder of rats with type 2 diabetes.

Diabetic cystopathy: A review

Herein we review and discuss epidemiological, clinical, and experimental studies on diabetic cystopathy, a common chronic complication of diabetes mellitus with a variety of lower urinary tract symptoms, providing directions for future research. A search of published epidemiological, clinical, or preclinical trial literature was performed using the key words "diabetes", "diabetic cystopathy", "diabetic bladder dysfunction", "diabetic lower urinary tract dysfunction", "diabetic detrusor instability". The classic symptoms of diabetic cystopathy are decreased bladder sensation, increased bladder capacity, and impaired bladder emptying with resultant increased post-void residual volume. However, recent clinical evidence indicates a presence of storage symptoms, such as overactive bladder symptoms. The pathophysiology of diabetic cystopathy is multifactorial, including disturbances of the detrusor, neuron, urothelium, and urethra. Hyperglycemia, oxidative stress, and polyuria play important roles in inducing voiding dysfunction in diabetic individuals. Treatment choice depends on clinical symptoms and urodynamic abnormalities. Urodynamic evaluation is the cornerstone of diagnosis and determines management strategies. Diabetes mellitus could cause a variety of lower urinary tract symptoms, leading to diabetic cystopathy with broadly varied estimates of the prevalence rates. The exact prevalence and pathogenesis of diabetic cystopathy remains to be further investigated and studied in multicenter, large-scaled, or randomized basic and clinical trials, and a validated and standardized workup needs to be made, improving diabetic cystopathy management in clinical practice. Further studies involving only female diabetics are recommended.

Grape Seed Proanthocyanidin Extract Ameliorates Diabetic Bladder Dysfunction via the Activation of the Nrf2 Pathway

Diabetes Mellitus (DM)-induced bladder dysfunction is predominantly due to the long-term oxidative stress caused by hyperglycemia. Grape seed proanthocyanidin extract (GSPE) has been reported to possess a broad spectrum of pharmacological and therapeutic properties against oxidative stress. However, its protective effects against diabetic bladder dysfunction have not been clarified. This study focuses on the effects of GSPE on bladder dysfunction in diabetic rats induced by streptozotocin. After 8 weeks of GSPE administration, the bladder function of the diabetic rats was improved significantly, as indicated by both urodynamics analysis and histopathological manifestation. Moreover, the disordered activities of antioxidant enzymes (SOD and GSH-Px) and abnormal oxidative stress levels were partly reversed by treatment with GSPE. Furthermore, the level of apoptosis in the bladder caused by DM was decreased following the administration of GSPE according to the Terminal Deoxynucleotidyl Transferase (TdT)-mediated dUTP Nick-End Labeling (TUNEL) assay. Additionally, GSPE affected the expression of apoptosis-related proteins such as Bax, Bcl-2 and cleaved caspase-3. Furthermore, GSPE showed neuroprotective effects on the bladder of diabetic rats, as shown by the increased expression of nerve growth factor (NGF) and decreased expression of the precursor of nerve growth factor (proNGF). GSPE also activated nuclear erythroid2-related factor2 (Nrf2), which is a key antioxidative transcription factor, with the concomitant elevation of downstream hemeoxygenase-1 (HO-1). These findings suggested that GSPE could ameliorate diabetic bladder dysfunction and decrease the apoptosis of the bladder in diabetic rats, a finding that may be associated with its antioxidant activity and ability to activate the Nrf2 defense pathway.

Bladder function in mice with inducible smooth muscle-specific deletion of the manganese superoxide dismutase gene

Manganese superoxide dismutase (MnSOD) is considered a critical component of the antioxidant systems that protect against oxidative damage. We are interested in the role of oxidative stress in bladder detrusor smooth muscle (SM) in different disease states. In this study, we generated an inducible, SM-specific Sod2(-/-) mouse model to investigate the effects of MnSOD depletion on the function of the bladder. We crossbred floxed Sod2 (Sod2(lox/lox)) mice with mice containing heterozygous knock-in of a gene encoding a tamoxifen-activated Cre recombinase in the SM22α promoter locus [SM-CreER(T2)(ki)(Cre/+)]. We obtained Sod2(lox/lox),SM-CreER(T2)(ki)(Cre/+) mice and injected 8-wk-old males with 4-hydroxytamoxifen to induce Cre-mediated excision of the floxed Sod2 allele. Twelve weeks later, SM-specific deletion of Sod2 and depletion of MnSOD were confirmed by polymerase chain reaction, immunoblotting, and immunohistochemistry. SM-specific Sod2(-/-) mice exhibited normal growth with no gross abnormalities. A significant increase in nitrotyrosine concentration was found in bladder SM tissue of SM-specific Sod2(-/-) mice compared with both wild-type mice and Sod2(+/+), SM-CreER(T2)(ki)(Cre/+) mice treated with 4-hydroxytamoxifen. Assessment of 24-h micturition in SM-specific Sod2(-/-) mice revealed significantly higher voiding frequency compared with both wild-type and SM-specific Cre controls. Conscious cystometry revealed significantly shorter intercontraction intervals and lower functional bladder capacity in SM-specific Sod2(-/-) mice compared with wild-type mice. This novel model can be used for exploring the mechanistic role of oxidative stress in organs rich in SM in different pathological conditions.

Tissue specific dysregulated protein subnetworks in type 2 diabetic bladder urothelium and detrusor muscle

Diabetes mellitus is well known to cause bladder dysfunction; however, the molecular mechanisms governing this process and the effects on individual tissue elements within the bladder are poorly understood, particularly in type 2 diabetes. A shotgun proteomics approach was applied to identify proteins differentially expressed between type 2 diabetic (TallyHo) and control (SWR/J) mice in the bladder smooth muscle and urothelium, separately. We were able to identify 1760 nonredundant proteins from the detrusor smooth muscle and 3169 nonredundant proteins from urothelium. Pathway and network analysis of significantly dysregulated proteins was conducted to investigate the molecular processes associated with diabetes. This pinpointed ERK1/2 signaling as a key regulatory node in the diabetes-induced pathophysiology for both tissue types. The detrusor muscle samples showed diabetes-induced increased tissue remodeling-type events such as Actin Cytoskeleton Signaling and Signaling by Rho Family GTPases. The diabetic urothelium samples exhibited oxidative stress responses, as seen in the suppression of protein expression for key players in the NRF2-Mediated Oxidative Stress Response pathway. These results suggest that diabetes induced elevated inflammatory responses, oxidative stress, and tissue remodeling are involved in the development of tissue specific diabetic bladder dysfunctions. Validation of signaling dysregulation as a function of diabetes was performed using Western blotting. These data illustrated changes in ERK1/2 phosphorylation as a function of diabetes, with significant decreases in diabetes-associated phosphorylation in urothelium, but the opposite effect in detrusor muscle. These data highlight the importance of understanding tissue specific effects of disease process in understanding pathophysiology in complex disease and pave the way for future studies to better understand important molecular targets in reversing bladder dysfunction.

Diabetic bladder dysfunction

OBJECTIVE

To review studies on diabetic bladder dysfunction (DBD), a common and bothersome complication of diabetes mellitus.

DATA SOURCES

We performed a search of the English literature through PubMed. The key words used were "diabetes" and "bladder dysfunction" or "cystopathy". Our own data and perspective are included in the discussion.

STUDY SELECTION

Studies containing data relevant to DBD were selected. Because of the limited length of this article, we also referenced reviews that contain comprehensive amalgamations of relevant literature.

RESULTS

The classic symptoms of DBD are decreased bladder sensation, increased bladder capacity, and impaired bladder emptying with resultant elevated post-void residual urine. However, recent clinical and experimental evidence indicate a strong presence of storage problems such as urge incontinence in diabetes. Recent studies of DBD in animal models of type 1 diabetes have revealed temporal effects of diabetes, causing an early phase of compensatory bladder function and a later phase of decompensated bladder function. The pathophysiology of DBD is multifactorial, including disturbances of the detrusor, urothelium, autonomic nerves, and urethra. Polyuria and hyperglycemia play important but distinctive roles in induction of bladder dysfunction in type 1 diabetes. Polyuria causes significant bladder hypertrophy in the early stage of diabetes, whereas oxidative stress in the bladder caused by chronic hyperglycemia may play an important role in the late stage failure of bladder function.

CONCLUSIONS

DBD includes time-dependent and mixed manifestations. The pathological alterations include muscle, nerve, and urothelium. Polyuria and hyperglycemia independently contribute to the pathogenesis of DBD. Treatments for DBD are limited. Future clinical studies on DBD in type 1 and type 2 diabetes should be investigated separately. Animal studies of DBD in type 2 diabetes are needed, from the natural history to mechanisms. Further understanding of the molecular mechanisms of DBD will provide multiple potential targets for therapeutic intervention.

Protective effect of cyanidin-3-O-β-D-glucopyranoside fraction from mulberry fruit pigment against oxidative damage in streptozotocin-induced diabetic rat bladder

AIMS

To determine whether cyanidin-3-O-β-D-glucopyranoside (C3G) fraction from mulberry fruit pigment has protective effects against bladder dysfunction on streptozotocin-induced diabetic rats

METHODS

Sprague-Dawley rats were divided into three groups (n = 12 in each): normal, diabetes (DM), and DM treated with C3G fraction (DM + C3G). The DM and DM + C3G groups received a single injection of streptozotocin (50 mg/kg) intraperitoneally. Four weeks after the induction of diabetes, the DM + C3G group was treated with daily oral C3G (10 mg/kg) dissolved in water, for 8 weeks. After 12 weeks of streptozotocin injections, rats in each group underwent cystometrography and bladders were used for evaluation of apoptosis and oxidative stress.

RESULTS

The DM group showed a markedly lower maximal intravesical pressure than that observed in the control group, whereas rats in the DM + C3G group showed improved maximum intravesical pressure associated with minimization of apoptosis, and increased levels of Akt and Bad phosphorylation, implying inhibition of pro-apoptotic stimuli. The level of 8-hydroxy-2-deoxyguanosine, a marker of oxidative stress, was significantly greater in the DM group compared to the control group and it was significantly reduced in the C3G treated group. Immunoblotting revealed a significant decrease in the levels of the superoxide dismutase protein and nerve growth factor in the DM group compared with the control group; however, these proteins were upregulated in the DM + C3G group compared with the DM group.

CONCLUSIONS

The study is the first to suggest that C3G fraction have a potency to protect the bladder under conditions of diabetes-induced oxidative stress.

Roles of polyuria and hyperglycemia in bladder dysfunction in diabetes

PURPOSE

Diabetes mellitus causes diabetic bladder dysfunction. We identified the pathogenic roles of polyuria and hyperglycemia in diabetic bladder dysfunction in rats.

MATERIALS AND METHODS

A total of 72 female Sprague-Dawley® rats were divided into 6 groups, including age matched controls, and rats with sham urinary diversion, urinary diversion, streptozotocin induced diabetes mellitus after sham urinary diversion, streptozotocin induced diabetes mellitus after urinary diversion and 5% sucrose induced diuresis after sham urinary diversion. Urinary diversion was performed by ureterovaginostomy 10 days before diabetes mellitus induction. Animals were evaluated 20 weeks after diabetes mellitus or diuresis induction. We measured 24-hour drinking and voiding volumes, and cystometry. Bladders were harvested to quantify smooth muscle, urothelium and collagen. We measured nitrotyrosine and Mn superoxide dismutase in the bladder.

RESULTS

Diabetes and diuresis caused increases in drinking and voiding volume, and bladder weight. Bladder weight decreased in the urinary diversion group and the urinary diversion plus diabetes group. The intercontractile interval, voided volume and compliance increased in the diuresis and diabetes groups, decreased in the urinary diversion group and further decreased in the urinary diversion plus diabetes group. Total cross-sectional tissue, smooth muscle and urothelium areas increased in the diuresis and diabetes groups, and decreased in the urinary diversion and urinary diversion plus diabetes groups. As a percent of total tissue area, collagen decreased in the diuresis and diabetes groups, and increased in the urinary diversion and urinary diversion plus diabetes groups. Smooth muscle and urothelium decreased in the urinary diversion and urinary diversion plus diabetes groups. Nitrotyrosine and Mn superoxide dismutase increased in rats with diabetes and urinary diversion plus diabetes.

CONCLUSIONS

Polyuria induced bladder hypertrophy, while hyperglycemia induced substantial oxidative stress in the bladder, which may have a pathogenic role in late stage diabetic bladder dysfunction.