Excitatory purinergic and cholinergic expression changed in a partial bladder outlet obstruction-induced overactive bladder rat model.

Overactive bladder (OAB) is a common, long-term symptom complex with a high prevalence in women worldwide. OAB has caused a social burden, and effective treatments are urgently needed. However, the pathogenesis of OAB has yet to be elucidated. Model rats underwent bladder outlet obstruction surgery. In the 2nd, 3rd, and 4th weeks after surgery, metabolic cages were used to detect the 12 h urine volume of rats in the sham and model groups. The urodynamic parameters bladder leak point pressure (BPLL), maximum voiding pressure (MVP), residual volume (RV), maximum bladder capacity (MBC), bladder compliance (BC), voided efficiency (VE), and non-voiding contractions (NVCs) were also detected. Moreover, the contractile responses of isolated detrusor muscles to electrical and carbachol stimulation were examined at the abovementioned time points. At the 4th week after surgery, the bladders of both groups were obtained for hematoxylin-eosin (H&E) and Masson's trichrome staining. Real-time qPCR and Western blot were performed to quantify the expression of choline acetyltransferase (ChAT) and solute carrier family 17 member 9 (SLC17A9). At week 4, compared with the sham group, the 12 h urine volume of PBOO group increased significantly. The BLPP, MVP, VE, MBC, and NVCs increased significantly, and the VE was significantly reduced in 4-week PBOO group. The contractile responses of isolated detrusor muscles to electrical and carbachol stimulation significantly increased in 4-week PBOO group. In the 4-week PBOO group, the bladder wall and the ratio of bladder muscle to collagen within the bladder smooth muscle layer wall were significantly higher than those in the sham group. ChAT and SLC17A9 mRNA and protein expression in the OAB model rats significantly increased. At 4 weeks after PBOO, the OAB model was successfully established. The gene and protein expression levels of ChAT and SLC17A9 increased in the bladder of the OAB model, suggesting that OAB may be related to increased excitatory purinergic and cholinergic expression.

Increased transient receptor potential canonical 3 activity is involved in the pathogenesis of detrusor overactivity by dynamic interaction with Na+/Ca2+ exchanger 1.

Transient receptor potential canonical 3 (TRPC3) is a nonselective cation channel, and its dysfunction is the basis of many clinical diseases. However, little is known about its possible role in the bladder. The purpose of this study was to explore the function and mechanism of TRPC3 in partial bladder outlet obstruction (PBOO)-induced detrusor overactivity (DO). We studied 31 adult female rats with DO induced by PBOO (the DO group) and 40 sham-operated rats (the control group). Here we report that the expression of TRPC3 in the bladder of DO rats increased significantly. Furthermore, PYR10, which can selectively inhibit the TRPC3 channel, significantly reduced bladder excitability in DO and control rats, but the decrease of the bladder excitability of DO rats was more obvious. PYR10 significantly reduced the intracellular calcium concentration in smooth muscle cells (SMCs) in DO and control rats. Finally, Na+/Ca2+ exchanger 1 (NCX1) colocalizes with TRPC3 and affects its expression and function. Collectively, these results indicate that TRPC3 plays an important role in the pathogenesis of DO through a synergistic effect with NCX1. TRPC3 and NCX1 may be new therapeutic targets for DO.

The surgical effect on overactive bladder symptoms in women with pelvic organ prolapse.

This study aimed to explore the effect of pelvic reconstruction surgery on the relation of pelvic organ prolapse (POP) and overactive bladder (OAB) and the impact of preoperative vaginal oestrogen supplement on vaginal tissue. A total of 100 postmenopausal women with symptomatic POP who underwent pelvic reconstruction surgery (laparoscopic sacrocolpopexy or transvaginal mesh) were enrolled in this study. Preoperative vaginal oestrogen was prescribed in 28 cases. The evaluation tools consisted of POP-Q, urodynamic study, Overactive Bladder Symptom Score (OABSS), and urinary NGF. Vaginal maturation index and vaginal specimens for hormone receptors study were investigated during operation to evaluate the effect of topical oestrogen. Follow-up assessments were performed at 1, 3, and 6 months after surgery. Preoperatively, 58 (58%) were POP with OAB. After reconstruction surgery, the OABSS decreased significantly (6.87 ± 0.85 vs 3.77 ± 0.61, p < 0.001) at postoperative 6 months in the group. Remarkable increasing trends of urinary NGF levels are noted till 3 months postoperatively, then decreasing to the baseline level at 6 months postoperative follow-up. Remarkable decrease of mRNA of the androgen receptor and significant higher expression of progesterone receptor (PR) were noted after use of the vaginal oestrogen cream. The severity of OAB in the POP women shows moderate degree according to OABSS. Pelvic reconstruction surgery can significantly improve the OAB symptoms. The surgery induced inflammation effect lasts for about 6 months. Short-term preoperative supplement of topical oestrogen brings alterations of the vaginal epithelium.

Association between the Trp64Arg polymorphism of the ADRB3 gene and overactive bladder.

BACKGROUND: The ß3 -adrenergic receptor (ADRB3) is very important in the regulation of the human detrusor muscle function. The well-known tryptophan64arginine polymorphism of the ADRB3 gene alters the response of the receptor to various stimuli, including adrenalin and noradrenalin, and may increase the susceptibility to develop overactive bladder (OAB). Therefore, this study was performed to determine whether ADRB3 Trp64Arg polymorphism is associated with the pathophysiology of OAB syndrome. METHODS: The study group (n = 150) consists of 72 patients with OAB and 78 controls without OAB. Venous blood samples were taken from all participants to analyze the ADRB3 gene Trp64Arg polymorphism using polymerase chain reaction (PCR)-restriction fragment length polymorphism (RFLP) assay. We compared the distribution of Trp64Arg polymorphism and symptom severity in both OAB and non-OAB subjects using χ2 test and Mann-Whitney's U test, respectively. RESULTS: The frequency of the 64Arg variant (heterozygous plus homozygous) in OAB and non-OAB subjects was 15.3% and 14.1%, respectively. There was no statistically significant difference between the OAB and non-OAB groups in regard to the distribution frequency of ADRB3 Trp64Arg polymorphism. The total frequency (OAB + non-OAB, 76 women and 74 men) of the Arg64 variant allele was 5.9% and 10.8% in women and in men, respectively. Although the frequency of the Arg64 variant was nearly twofold higher in men compared to women, the difference was not statistically significant. CONCLUSIONS: These results demonstrated that the ADRB3 Trp64Arg polymorphism is not significantly associated with OAB syndrome in a sample of Turkish OAB patients.

Relation of ADRB3, GEF, ROCK2 gene polymorphisms to clinical findings in overactive bladder.

PURPOSE: Adrenergic and cholinergic pathways play an important role in contraction-relaxation harmony in human bladder. Functional changes in any proteins in these pathways may result in overactive bladder. We aimed to investigate whether single gene polymorphisms affecting adrenergic and cholinergic pathways are associated with OAB syndrome. METHODS: 60 patients with idiopathic OAB and 60 healthy controls were included in the study. A validated OAB-V8 questionnaire was given to all patients. Polymorphisms of ADRB3, ROCK2, and GEF gene were detected by PCR from whole blood samples. Genotypic structures of patients and controls were compared. The relationship between genotypic structures and OAB symptom scores were investigated. RESULTS: We found no significant difference in the genotype and allele frequencies between the patients and controls for all three SNP. While there was no relationship between ADRB3 and GEF gene polymorphisms and OAB scores in OAB patients, the OAB score in heterozygous polymorphic individuals was significantly higher than in homozygous polymorphic individuals in the ROCK2 gene (p = 0.039). CONCLUSION: The polymorphisms of the ADRB3, ROCK2, and GEF genes were present in both OAB group and healthy controls, but were not associated with OAB syndrome.

Exploring biomarkers in the overactive bladder: Alterations in miRNA levels of a panel of genes in patients with OAB.

AIMS: It has been demonstrated that there are abundant stable microRNAs (miRNAs) in plasma, which is potentially disease-specific. Adrenergic and muscarinic pathways play an important role in voiding physiology. Alterations in the levels of miRNAs are thought to influence the regulation of these pathways at the molecular level. The aim of this study was to investigate the relationship of miRNAs with overactive bladder pathogenesis and to provide a new perspective to treatment approaches. METHODS: This study included patients with an overactive bladder (OAB) diagnosis and a healthy control group. All patients completed a validated OAB-V8 questionnaire. The relative expression levels of 12 miRNAs were examined in plasma by PCR. Receiver operating characteristic (ROC) curves were generated to evaluate the diagnostic qualification of miRNAs. RESULTS: The relative expression levels of let-7b-5p, miR-92a-3p, miR-98-5p, miR-142-3p, and miR-200c-3p were significantly upregulated and miR-139-5p was significantly downregulated in patients with OAB and no correlation was determined between the levels of miRNAs with OAB symptom score. Among the miRNAs, miR-98-5p provided the highest diagnostic accuracy alone (area under curve [AUC] = 0.79) in ROC analysis. The combination of miR-98-5p + miR-139-5p was seen to be a good indicator (AUC = 0.839). CONCLUSIONS: These results suggest that alteration of the miRNA levels can be used as auxiliary parameters to explain the pathophysiology of OAB syndrome and could shed light on new treatment options.

Polymorphism in the interleukin-10 gene is associated with overactive bladder phenotype associated with HTLV-1 infection.

INTRODUCTION: Human T-cell lymphotropic virus type 1 (HTLV-1)-associated inflammatory diseases are not well understood; however, their clinical manifestations may be influenced by the host genetic background. METHODS: We genotyped 298 individuals with HTLV-1 and 380 controls for interleukin-10 (IL10) gene variants-rs3024496, rs1800871, rs1800896-and used logistic regression analysis to determine their association with clinical phenotypes. RESULTS: No association with HTLV-1 infection was observed. However, allele A of rs1800896 (1082bp upstream) was associated with protection against neurological impairment, specifically overactive bladder (OR=0.447, 95% CI 0.28-0.70, p=0.001). CONCLUSIONS: Our data suggests that IL10 regulation ameliorates neurological damage in HTLV-1 infections.

Urinary Biomarkers in Overactive Bladder: Revisiting the Evidence in 2019.

CONTEXT: In overactive bladder (OAB), after an initial outbreak of research, it is more consensual that biomarkers may be better used to phenotype patients. Herein, we revisit this topic, including some of the most promising biomarkers. OBJECTIVE: To provide a comprehensive analysis of the actual role of biomarkers in OAB. EVIDENCE ACQUISITION: A PubMed-based literature search was conducted, including the most relevant articles published in the last 15 yr, on nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), adenosine triphosphate (ATP), genomics, and microbiota as OAB biomarkers. Articles with no full text available or not written in English were excluded. Additional reviews were included. EVIDENCE SYNTHESIS: Urinary NGF, BDNF, and ATP are increased in many OAB patients. These biomarkers can help identify OAB phenotypes and select the ideal candidates for new therapies directed to neurotrophic and purinergic pathways. Circulating urinary miRNA may be useful for establishing the ideal moment for bladder outlet obstruction relief and will eventually lead to the development of therapeutic agents that inhibit or reverse fibrotic pathways in the bladder. Urinary microbiota seems to be related to OAB symptoms, in particular urgency urinary incontinence, and may have strong implications in the prevention, diagnosis, and treatment of OAB. CONCLUSIONS: In the future, physicians may consider the use of biomarkers to identify distinct OAB phenotypes, with distinct causal mechanisms, selecting patients for specific target therapies with expected better outcomes. PATIENT SUMMARY: Overactive bladder biomarkers can be useful for phenotype patients and for selecting more effective target therapies.

Role of ß-3 adrenergic receptor polymorphism in overactive bladder.

AIMS: Women with overactive bladder (OAB) have a higher frequency of a single-nucleotide polymorphism (SNP) at codon 64 of the ß-3 adrenergic receptor gene (ADRB3). Since the SNP results in an amino acid substitution that could theoretically alter receptor protein function, we hypothesized that those with the SNP would display greater OAB symptom severity. Therefore we aimed to compare OAB severity between women with this SNP and women with the wild type genotype. METHODS: A retrospective cohort study was performed in women with bothersome OAB from two academic institutions. Banked blood samples were tested for the codon 64 SNP. Women were divided into two groups based on genotype: wild-type (WT) and heterozygous (HZ). We compared mean OAB Symptom Severity questionnaire (OAB-q) scores between groups using t tests. Linear regression was performed to control for potential confounders. RESULTS: Of the 303 women with OAB, 254 (83.8%) had the WT genotype, and 49 (16.2%) the HZ genotype. There were no homozygous women for the rare allele. The majority were Caucasian (86%) and non-Hispanic (97%). There were no significant differences in mean OAB-q symptom severity scores (WT 21.2 ± 7 vs HZ 22.0 ± 6.6; P = 0.49) and quality of life scores (WT 39.6 ± 15.5 vs HZ 39.1 ± 16.6; P = 0.83) between groups. These remained nonsignificant in a linear regression model. CONCLUSIONS: In a predominantly non-Hispanic, Caucasian population of women with bothersome OAB, symptom severity was not related to ADRB3 codon 64 SNP genotype.

Association of genetic polymorphisms in the pore domains of mechano-gated TREK-1 channel with overactive lower urinary tract symptoms in humans.

AIMS: Mechanosensitivity of the urinary bladder is regulated by many factors including mechano-gated two-pore domain (K2 P, KCNK) potassium channels. TWIK-related K+ channel, TREK-1, is a predominantly expressed member of K2 P channel family in the human detrusor, and its expression and function are diminished in patients with overactive lower urinary tract symptoms (LUTS). The changes in channel activity may result from spontaneously occurring gene mutations. The aim of this study was to compare single nucleotide polymorphisms (SNPs) in TREK-1 channel between patients with LUTS and healthy donors. METHODS: Six SNPs (rs370266806, rs373919966, rs758937019, rs769301539, rs772497750, and rs775158737) in two pore domains of human TREK-1 gene were analyzed using TaqMan SNP genotyping assay with manufacturer-designed primers and allele-specific probes. The screening was done in control bladders and detrusor specimens from patients with overactive LUTS. Statistical analyses were performed using R, Fisher's exact test and Hardy-Weinberg Equilibrium. RESULTS: Six SNPs in two pore domains of the human TREK-1 gene were analyzed in human bladder specimens. The frequencies of rs758937019-CT genotype (P = 0.0016) and rs758937019-T allele (P = 0.0022) were significantly higher in the group with overactive LUTS. There was no significant association of rs775158737-GA genotype and rs775158737-A allele with the overactive LUTS, though they were present only in the overactive LUTS group. CONCLUSIONS: Our results provide evidence that altered expression and function of TREK-1 channel in patients with overactive LUTS could be due to genetic polymorphisms in the pore domains of TREK-1 channel (rs758937019).

Effect of high-fat diet-induced obesity on the small-conductance Ca2+-activated K+ channel function affecting the contractility of rat detrusor smooth muscle.

PURPOSE: Obesity usually induces overactive bladder (OAB) associated with detrusor overactivity, which is related to increased contractility of the detrusor smooth muscle (DSM). Small-conductance Ca2+-activated K+ (SK) channels play a constitutive role in the regulation of DSM contractility. However, the role of SK channels in the DSM changes in obesity-related OAB is still unknown. Here, we tested the hypothesis that obesity-related OAB is associated with reduced expression and activity of SK channels in DSM and that SK channels activation is a potential treatment for OAB. METHODS: Female Sprague-Dawley rats were fed a normal diet (ND) or a high-fat diet (HFD) and weighed after 12 weeks. Urodynamic studies, quantitative reverse transcription-polymerase chain reaction (qRT-PCR), and isometric tension recording were performed. RESULTS: Increased average body weights and urodynamically demonstrated OAB were observed in HFD rats. qRT-PCR experiments revealed a decrease in the mRNA expression level of SK channel in DSM tissue of the HFD rats. Isometric tension recordings indicated an attenuated relaxation effect of NS309 on the spontaneous phasic and electrical field stimulation-induced contractions that occurred via SK channel activation in HFD DSM strips. CONCLUSIONS: Reduced expression and activity of SK channels in the DSM contribute to obesity-related OAB, indicating that SK channels are a potential therapeutic target for OAB.

Polymorphism in the interleukin-10 gene is associated with overactive bladder phenotype associated with HTLV-1 infection

Abstract INTRODUCTION Human T-cell lymphotropic virus type 1 (HTLV-1)-associated inflammatory diseases are not well understood; however, their clinical manifestations may be influenced by the host genetic background. METHODS We genotyped 298 individuals with HTLV-1 and 380 controls for interleukin-10 (IL10) gene variants-rs3024496, rs1800871, rs1800896-and used logistic regression analysis to determine their association with clinical phenotypes. RESULTS No association with HTLV-1 infection was observed. However, allele A of rs1800896 (1082bp upstream) was associated with protection against neurological impairment, specifically overactive bladder (OR=0.447, 95% CI 0.28-0.70, p=0.001). CONCLUSIONS Our data suggests that IL10 regulation ameliorates neurological damage in HTLV-1 infections.

Mouse urothelial genes associated with voiding behavior changes after ovariectomy and bladder lipopolysaccharide exposure.

AIMS: Symptoms from overactive bladder (OAB) and cystitis secondary to urinary tract infection (UTI) can be similar in post-menopausal women. Effects of ovariectomy (OVX) on voiding behavior after lipopolysaccharide (LPS) intravesical exposure (surrogate for cystitis) in mice were measured. Urothelial genes associated with micturition changes were identified. METHODS: Female C57BL6/J mice underwent OVX or sham surgeries (n = 10 for each). Voiding spot assays (VSA) were performed prior to surgery, 4 weeks post-surgery, and each time after 3 consecutive days of transurethral instillation of LPS. In another experiment, mice underwent either sham (n = 9) or OVX (n = 9) surgeries. Urothelial RNAs were collected 4 weeks post-surgery, day 1 and day 3 after LPS instillation. Mouse Gene 2.0 ST Arrays (entire 34 K transcripts) were used for microarray hybridization. A set of criteria was utilized to identify gene expression changes that mimicked voiding behavior changes. RESULTS: Three days after LPS exposure, OVX mice persisted with overactive whereas sham mice normalized voiding behavior. Nine urothelial paralleling voiding behavior changes were identified: IL6 (interleukin 6), IL6rα (Interleukin 6 receptor α), Ptgs2 (Prostaglandin-endoperoxide synthase 2 or COX-2), Ereg (epiregulin), Dusp6 (dual specificity phosphatase 6), Zfp948 (zinc finger protein 948), Zfp52 (Zinc finger protein 52), Gch1 (GTP cyclohydrolase 1), and Amd (S-adenosylmethionine decarboxylase). Three other genes, coding unknown proteins, were also identified: GM12840, GM23134, and GM26809. CONCLUSIONS: OVX mice persisted with increased voiding frequency after LPS. Urothelial genes that could mediate this voiding behavior include IL6, COX-2, and S-adenosylmethionine decarboxylase.

Increased Expression of TREK-1 K+ Channel in the Dorsal Root Ganglion of Rats with Detrusor Overactivity After Partial Bladder Outlet Obstruction.

BACKGROUND Changes in expression and activity of ion channels are important pathophysiological mechanisms underlying detrusor overactivity (DO) in partial bladder outlet obstruction (PBOO). The objective of this study was to examine the expression of TREK-1 channel in the bladder and central nervous system of DO rats. MATERIAL AND METHODS Thirty Sprague-Dawley rats were subjected to PBOO operations and those displaying non-voiding contractions (NVCs) in cystometry were classified as DO. Sham-operated rats without NVCs in cystometry served as controls. The expression and distribution of TREK-1 in the bladder, spinal cord, and dorsal root ganglion (DRG) were detected by real time-PCR, western blot, and immunohistochemistry. RESULTS TREK-1 channel expression in the DRG was significantly increased at the mRNA level (11.20±3.762 vs. 3.209±1.505, P<0.01) and protein level (2.195±0.058 vs. 1.713±0.066, P<0.01) in DO rats as compared to control rats. However, the expression of TREK-1 mRNA in the bladder (1.380±0.810 vs. 4.206±3.827, P>0.05) and spinal cord (0.764±0.357 vs. 0.696±0.188, P>0.05) was comparable between the 2 groups. Immunohistochemistry showed enhanced immunoreactive signals of TREK-1 channel in the DRG, but not in the spinal cord and bladder. CONCLUSIONS TREK-1 channel was upregulated in the DRG of DO rats after chronic PBOO, which might suppress neuronal excitability and play a protective role in bladder overactivity in PBOO.

Muscarinic receptors 2 and 5 regulate bitter response of urethral brush cells via negative feedback.

We have recently identified a cholinergic chemosensory cell in the urethral epithelium, urethral brush cell (UBC), that, upon stimulation with bitter or bacterial substances, initiates a reflex detrusor activation. Here, we elucidated cholinergic mechanisms that modulate UBC responsiveness. We analyzed muscarinic acetylcholine receptor (M1-5 mAChR) expression by using RT-PCR in UBCs, recorded [Ca2+]i responses to a bitter stimulus in isolated UBCs of wild-type and mAChR-deficient mice, and performed cystometry in all involved strains. The bitter response of UBCs was enhanced by global cholinergic and selective M2 inhibition, diminished by positive allosteric modulation of M5, and unaffected by M1, M3, and M4 mAChR inhibitors. This effect was not observed in M2 and M5 mAChR-deficient mice. In cystometry, M5 mAChR-deficient mice demonstrated signs of detrusor overactivity. In conclusion, M2 and M5 mAChRs attenuate the bitter response of UBC via a cholinergic negative autocrine feedback mechanism. Cystometry suggests that dysfunction, particularly of the M5 receptor, may lead to such symptoms as bladder overactivity.-Deckmann, K., Rafiq, A., Erdmann, C., Illig, C., Durschnabel, M., Wess, J., Weidner, W., Bschleipfer, T., Kummer, W. Muscarinic receptors 2 and 5 regulate bitter response of urethral brush cells via negative feedback.

MicroRNAs as potential biomarkers to predict the risk of urinary retention following intradetrusor onabotulinumtoxin-A injection.

AIMS: MicroRNAs (miRs) control post-transcriptional gene expression, and this is relevant in understanding better chronic diseases and treatment outcomes. The role of miRs in the pathology and treatment outcomes of overactive bladder (OAB) is unknown. In this study, we assessed the differential expression of miRs in OAB patients responding with either normal or elevated post-void residual volumes (PVRs) ≥200 mL following intradetrusor injection of onabotulinumtoxin-A (onaBoNT-A). METHODS: Female OAB patients refractory to OAB drugs were consented for this study. Cystoscopic-guided punch bladder biopsy was obtained at the time of injection of onaBoNT-A 100 units. The expression of 13 miR species, selected for their known effect on neurotrophin expression and smooth muscle function, was measured. PVRs and urine nerve growth factor (NGF) levels were measured at baseline and at the follow-up visit. RESULTS: Fourteen patients with mean age of 66 years were consented. Of these patients, nine maintained PVRs <200 mL after onaBoNT-A injection to comprise the low PVR group. The other five patients with PVRs ≥200 mL comprised the high PVR group. The expression of miR221 and miR125b was upregulated by 11- and 2-fold, respectively, in patients who responded with low PVRs after onaBoNT-A (P < 0.05). Urine NGF levels at baseline were not different between the two groups. CONCLUSIONS: This study suggests that deficiency in the pretreatment expression of miR221 and miR125b may predispose OAB patients to high PVRs following intradetrusor onaBoNT-A. Additional studies are needed to better understand the role of miRs in OAB.

Cross-Sectional Epidemiological Analysis of the Nagahama Study for Correlates of Overactive Bladder: Genetic and Environmental Considerations.

PURPOSE: The prevalence of overactive bladder is increasing globally. It has a substantial impact on quality of life and represents a heavy economic burden. We evaluated the prevalence of overactive bladder in a Japanese population and analyzed whether genetic and environmental factors influence overactive bladder. MATERIALS AND METHODS: This cross-sectional study was performed as part of the Nagahama cohort project. It comprised a questionnaire survey as well as anthropometric, physiological and biochemical measures, and genomic information on participants 30 to 74 years old in Nagahama, Japan. A genome-wide association study was performed in 4,645 participants, including 1,521 men and 3,124 women, using 99,059 single nucleotide polymorphisms. Univariate and multivariable logistic regression was done to analyze environmental factors associated with overactive bladder. RESULTS: The prevalence of overactive bladder was 11.8%, including 15.3% in men and 10.1% in women, and it increased with age. We found no significant association between overactive bladder and any single nucleotide polymorphism in the genome-wide association study. However, in the multivariable logistic regression model overactive bladder was positively associated with environmental factors, including age, depression and the consumption of cake or Japanese confection. CONCLUSIONS: The prevalence of overactive bladder was greater in men than in women, especially among the elderly. Environmental factors rather than genetic variants more likely contribute to overactive bladder.

BDNF overexpression in the bladder induces neuronal changes to mediate bladder overactivity.

Elevated levels of brain-derived neurotrophic factor (BDNF) in urine of overactive bladder (OAB) patients support the association of BDNF with OAB symptoms, but the causality is not known. Here, we investigated the functionality of BDNF overexpression in rat bladder following bladder wall transfection of either BDNF or luciferase (luciferase) transgenes (10 µg). One week after transfection, BDNF overexpression in bladder tissue and elevation of urine BDNF levels were observed together with increased transcript of BDNF, its cognate receptors (TrkB and p75NTR), and downstream PLCγ isoforms in bladder. BDNF overexpression can induce the bladder overactivity (BO) phenotype which is demonstrated by the increased voiding pressure and reduced intercontractile interval during transurethral open cystometry under urethane anesthesia. A role for BDNF-mediated enhancement of prejunctional cholinergic transmission in BO is supported by the significant increase in the atropine- and neostigmine-sensitive component of nerve-evoked contractions and upregulation of choline acetyltransferase, vesicular acetylcholine transporter, and transporter Oct2 and -α1 receptors. In addition, higher expression of transient receptor channels (TRPV1 and TRPA1) and pannexin-1 channels in conjunction with elevation of ATP and neurotrophins in bladder and also in L6/S1 dorsal root ganglia together support a role for sensitized afferent nerve terminals in BO. Overall, genomic changes in efferent and afferent neurons of bladder induced by the overexpression of BDNF per se establish a mechanistic link between elevated BDNF levels in urine and dysfunctional voiding observed in animal models and in OAB patients.