Involvement of urinary bladder Connexin43 and the circadian clock in coordination of diurnal micturition rhythm

How should we assess the cardiovascular system in patients presenting with bothersome nocturia? ICI-RS 2023

AIMS

The link between nocturia and cardiovascular disease (CVD) is frequently discussed in literature, yet the precise nature of this relationship remains poorly characterized. The existing literature was reviewed in order to address issues concerning the origin, diagnosis, management, and implications of the co-occurrence of CVD and nocturia.

METHODS

This review summarizes literature and recommendations regarding the link between CVD and nocturia discussed during a think-tank meeting held at the 2023 International Consultation on Incontinence-Research Society.

RESULTS

Cardiovascular disorders are often underestimated contributors to nocturia, with various potential mechanisms influencing nighttime urination, such as impact on fluid retention, atrial natriuretic peptide, and glomerular filtration rate. The redistribution of fluid from leg edema in supine position can lead nocturnal polyuria (NP). Additionally, sleep disturbances due to nocturia in itself may lead to CVD through an increase in blood pressure, insulin resistance, and inflammation. Disrupted circadian rhythms (e.g., in sleep pattern and urine production) were identified as critical factors in most etiologies of nocturia, and their contribution is deemed imperative in future research and treatment approaches, particularly in the aging population. NP can be detected through a simple bladder diary and can even be used to distinguish cardiac from noncardiac causes of nocturia. For the treatment of NP, desmopressin can be effective in select patients, however, caution and close monitoring is warranted for those with CVD due to increased risk of side effects.

CONCLUSIONS

Gaps were identified in the available evidence and clear cut recommendations were put forth for future research. It is essential to gain a deeper understanding of the mechanisms linking nocturia and CVD to develop optimal management strategies.

Regulation of protein O-GlcNAcylation by circadian, metabolic, and cellular signals

O-linked β-N-acetylglucosamine (O-GlcNAcylation) is a dynamic post-translational modification that regulates thousands of proteins and almost all cellular processes. Aberrant O-GlcNAcylation has been associated with numerous diseases, including cancer, neurodegenerative diseases, cardiovascular diseases, and type 2 diabetes. O-GlcNAcylation is highly nutrient-sensitive since it is dependent on UDP-GlcNAc, the end product of the hexosamine biosynthetic pathway (HBP). We previously observed daily rhythmicity of protein O-GlcNAcylation in a Drosophila model that is sensitive to the timing of food consumption. We showed that the circadian clock is pivotal in regulating daily O-GlcNAcylation rhythms given its control of the feeding-fasting cycle and hence nutrient availability. Interestingly, we reported that the circadian clock also modulates daily O-GlcNAcylation rhythm by regulating molecular mechanisms beyond the regulation of food consumption time. A large body of work now indicates that O-GlcNAcylation is likely a generalized cellular status effector as it responds to various cellular signals and conditions, such as ER stress, apoptosis, and infection. In this review, we summarize the metabolic regulation of protein O-GlcNAcylation through nutrient availability, HBP enzymes, and O-GlcNAc processing enzymes. We discuss the emerging roles of circadian clocks in regulating daily O-GlcNAcylation rhythm. Finally, we provide an overview of other cellular signals or conditions that impact O-GlcNAcylation. Many of these cellular pathways are themselves regulated by the clock and/or metabolism. Our review highlights the importance of maintaining optimal O-GlcNAc rhythm by restricting eating activity to the active period under physiological conditions and provides insights into potential therapeutic targets of O-GlcNAc homeostasis under pathological conditions.

Role of ecto-5'-nucleotidase in bladder function

Purinergic signaling plays an important role in regulating bladder contractility and voiding. Abnormal purinergic signaling is associated with lower urinary tract symptoms (LUTS). Ecto-5'-nucleotidase (NT5E) catalyzes dephosphorylation of extracellular AMP to adenosine, which in turn promotes adenosine-A2b receptor signaling to relax bladder smooth muscle (BSM). The functional importance of this mechanism was investigated using Nt5e knockout (Nt5eKO) mice. Increased voiding frequency of small voids revealed by voiding spot assay was corroborated by urodynamic studies showing shortened voiding intervals and decreased bladder compliance. Myography indicated reduced contractility of Nt5eKO BSM. These data support a role for NT5E in regulating bladder function through modulation of BSM contraction and relaxation. However, the abnormal bladder phenotype of Nt5eKO mice is much milder than we previously reported in A2b receptor knockout (A2bKO) mice, suggesting compensatory response(s) in Nt5eKO mouse bladder. To better understand this compensatory mechanism, we analyzed changes in purinergic and other receptors controlling BSM contraction and relaxation in the Nt5eKO bladder. We found that the relative abundance of muscarinic CHRM3 (cholinergic receptor muscarinic 3), purinergic P2X1, and A2b receptors was unchanged, whereas P2Y12 receptor was significantly downregulated, suggesting a negative feedback response to elevated ADP signaling. Further studies of additional ecto-nucleotidases indicated significant upregulation of the nonspecific urothelial alkaline phosphatase ALPL, which might mitigate the degree of voiding dysfunction by compensating for Nt5e deletion. These data suggest a mechanistic complexity of the purinergic signaling network in bladder and imply a paracrine mechanism in which urothelium-released ATP and its rapidly produced metabolites coordinately regulate BSM contraction and relaxation.

Functional Characterization of Circadian Nuclear Receptors REV-ERBα and REV-ERBβ in Human Osteosarcoma Cell Cultures

REV-ERBα and its paralog, REV-ERBβ, encoded by NR1D1 and NR1D2 genes, are key nuclear receptors that link the circadian timing system and metabolic homeostasis. Since heme is an endogenous ligand, REV-ERBs have been considered key components of the circadian molecular clock and can be pharmacologically targeted to treat various circadian rhythm-related diseases, such as cardiometabolic, inflammatory, and neuropsychiatric diseases, as well as cancer. REV-ERBs are believed to be functionally redundant and compensatory, although they often affect the expression of gene subsets in an isoform-specific manner. Therefore, this study aimed to identify the redundant and distinct roles of each isoform in controlling its target genes by comparing the transcriptome profiles of a panel of mutant U2OS human osteosarcoma cells in which either NR1D1 or NR1D2 was ablated. Indeed, our transcriptomic analyses revealed that most REV-ERB-regulated genes are controlled by redundant or even additive actions. However, the RNA expression profiles of each single mutant cell line also provide strong evidence for isoform-dependent actions. For example, REV-ERBα is more responsible for regulating the NF-κΒ signaling pathway, whereas a group of extracellular matrix components requires REV-ERBβ to maintain their expression. We found that REV-ERBs have isoform-selective functions in the regulation of certain circadian output pathways despite their overlapping roles in the circadian molecular clock. Thus, the development of isoform-selective REV-ERB modulators can help treat metabolic disturbances and certain types of cancer.

Sleep quality and obstructive sleep apnea among male patients with lower urinary tract symptoms: A prospective observational study

Introduction

Apart from nocturia, few reports have been published on the relationship between lower urinary tract symptoms (LUTS) and sleep disturbances in patients visiting urology outpatient clinics. This study assessed the association between our population's LUTS and sleep disturbances.

Methods

This was a prospective observational study. A total of 123 male patients with a history of LUTS aged more than 40 years were recruited from urology outpatient clinic. International Prostate Symptom Score was utilized to assess LUTS. To determine the quality of sleep, the Pittsburgh Sleep Quality Index (PSQI) was used. Berlin questionnaire (BQ) was used for screening obstructive sleep apnea.

Results

A total of 123 participants were enrolled in this study. The mean age of the participants was 61 ± 11.1 years. Nocturia >3 episodes were significantly more in patients with PSQI >5 (P < 0.05). There was a greater prevalence of severe LUTS in patients with PSQI >5 (P < 0.05). The association between LUTS and BQ score showed an increased prevalence of severe symptoms in patients with high BQ. Patients with PSQI >5 had more severe LUTS (53% of patients) compared to patients with PSQI ≤5 (5% of patients) (P = 0.000). Patients with PSQI >5 had overall poorer quality of life (QOL) scores, with QOL being 5 and 6 in 18% and 4.8% of the patients, respectively.

Conclusions

There is a significant association between the prevalence of nocturia, moderate-to-severe LUTS, and the existence of sleep disorders. Therefore, screening for sleep disturbances may be performed on male patients who present with LUTS.

Diurnal differences in urine flow in healthy young men in a light-controlled environment: a randomized crossover design

BACKGROUND

Older men often experience nocturnal urination difficulties, reflected by diurnal differences in maximum urine flow (Qmax). Since lower urinary tract symptoms and pathological comorbidities are frequent in older men, it remains unclear whether this diurnal variation is a physiological or pathological phenomenon. Our aim was to quantify the diurnal variability of Qmax in healthy young participants under varying daylight conditions in a stable environment to discern potential underlying causes of nocturnal urination difficulties.

METHODS

Twenty-one healthy young men were recruited in a 4-day study utilizing daytime (08:00-18:00) exposure with two light conditions in randomized order: dim (< 50 lx) or bright (~2500 lx). Day 1 was for acclimation, and urine flow was assessed from day 2. The participants urinated ad libitum during day 2 and then at fixed 3-4-h intervals thereafter (days 3-4). Regular urination Qmax at late night (04:00) on day 4 was compared with the nearest voided volume during daytime of day 3 (mDay).

RESULTS

Morning Qmax scores (after bed-11:00) on day 2 were significantly lower than evening (17:00-before pre-sleep) in bright conditions and those of daytime (11:00-17:00), evening (17:00-before pre-sleep), and pre-sleep in dim conditions. Pre-sleep Qmax during the ad libitum period was significantly higher in dim than bright conditions. Late-night Qmax values (04:00) on day 4 were significantly lower than Qmax scores of mDay on day 3 in both light conditions.

CONCLUSIONS

Healthy young men had a clear diurnal Qmax difference that decreased during late night and morning. In addition, the pre-sleep Qmax values in dim daylight were significantly higher than in bright daylight. Taken together, we conclude that late-night and morning decreases in Qmax are an instinctive physiological phenomenon in humans, and the diurnal difference of Qmax can be influenced by daylight conditions.

G protein-coupled receptor 55 activated by palmitoylethanolamide is associated with the development of nocturia associated with circadian rhythm disorders

AIMS

Bladder function is regulated by clock genes and dysregulation of circadian bladder function can cause nocturia. The blood concentration of palmitoylethanolamide (PEA), a fatty acid metabolite, changes with circadian rhythm. Clock gene abnormalities demonstrate the highest PEA levels during the sleep phase. PEA is a GPR55 agonist that influences urination; therefore, increased PEA during the sleep phase may cause nocturia. Herein, we investigated the function of GPR55 to evaluate the relationship between GPR55 and nocturia that evoked higher PEA during the sleep phase in patients with circadian rhythm disorders.

MAIN METHODS

Male C57BL/6 mice were used. GPR55 localization was evaluated by immunofluorescence staining, qRT-PCR, and western blotting. Variations in PEA-induced intracellular Ca2+ concentrations were measured in primary cultured mouse urothelial cells (UCs) using Ca2+ imaging. PEA-induced NGF and PGI2 release in UCs was measured by ELISA. The micturition reflex pathway after PEA administration was evaluated using immunofluorescence staining.

KEY FINDINGS

GPR55 was predominant in the UC layer. PEA induced release of Ca2+ from the endoplasmic reticulum into the UC cytoplasm. ELISA and immunofluorescence staining revealed that NGF and PGI2 were released from bladder UCs, stimulated the pontine micturition center in mice, and induced nocturia.

SIGNIFICANCE

The loss of regular circadian metabolizing rhythm in fatty acids causes higher blood PEA levels during the sleep phase. Binding of PEA to GPR55 in UC may activate the downstream processes of the micturition reflex, leading to nocturia. These findings suggest a new mechanism for nocturia and its potential as a therapeutic target.

Uncovering the Novel Role of NR1D1 in Regulating BNIP3-Mediated Mitophagy in Ulcerative Colitis

BACKGROUND

Ulcerative colitis (UC) is a chronic, incurable condition characterized by mucosal inflammation and intestinal epithelial cell (IEC) damage. The circadian clock gene NR1D1, implicated in UC and the critical mitophagy process for epithelial repair, needs further exploration regarding its role in mitophagy regulation in UC.

METHODS

We created a jet lag mouse model and induced colitis with dextran sulfate sodium (DSS), investigating NR1D1's role. Intestinal-specific Nr1d1 knockout mice were also generated. RNA sequencing, chromatin immunoprecipitation (ChIP), and dual-luciferase reporter assays helped ascertain NR1D1's regulatory effect on BNIP3 expression. The mitochondrial state in IECs was assessed through transmission electron microscopy, while confocal microscopy evaluated mitophagy-associated protein expression in colon tissue and CCD841 cells. Cell apoptosis and reactive oxygen species (ROS) were measured via flow cytometry.

RESULTS

We observed reduced NR1D1 expression in the IECs of UC patients, accentuated under jet lag and DSS exposure in mice. NR1D1 ablation led to disrupted immune homeostasis and declined mitophagy in IECs. NR1D1, usually a transcriptional repressor, was a positive regulator of BNIP3 expression, leading to impaired mitophagy, cellular inflammation, and apoptosis. Administering the NR1D1 agonist SR9009 ameliorated colitis symptoms, primarily by rectifying defective mitophagy.

CONCLUSIONS

Our results suggest that NR1D1 bridges the circadian clock and UC, controlling BNIP3-mediated mitophagy and representing a potential therapeutic target. Its agonist, SR9009, shows promise in UC symptom alleviation.

Circadian rhythms in colonic function

A rhythmic expression of clock genes occurs within the cells of multiple organs and tissues throughout the body, termed "peripheral clocks." Peripheral clocks are subject to entrainment by a multitude of factors, many of which are directly or indirectly controlled by the light-entrainable clock located in the suprachiasmatic nucleus of the hypothalamus. Peripheral clocks occur in the gastrointestinal tract, notably the epithelia whose functions include regulation of absorption, permeability, and secretion of hormones; and in the myenteric plexus, which is the intrinsic neural network principally responsible for the coordination of muscular activity in the gut. This review focuses on the physiological circadian variation of major colonic functions and their entraining mechanisms, including colonic motility, absorption, hormone secretion, permeability, and pain signalling. Pathophysiological states such as irritable bowel syndrome and ulcerative colitis and their interactions with circadian rhythmicity are also described. Finally, the classic circadian hormone melatonin is discussed, which is expressed in the gut in greater quantities than the pineal gland, and whose exogenous use has been of therapeutic interest in treating colonic pathophysiological states, including those exacerbated by chronic circadian disruption.

Somatic mutations of CADM1 in aldosterone-producing adenomas and gap junction-dependent regulation of aldosterone production

Aldosterone-producing adenomas (APAs) are the commonest curable cause of hypertension. Most have gain-of-function somatic mutations of ion channels or transporters. Herein we report the discovery, replication and phenotype of mutations in the neuronal cell adhesion gene CADM1. Independent whole exome sequencing of 40 and 81 APAs found intramembranous p.Val380Asp or p.Gly379Asp variants in two patients whose hypertension and periodic primary aldosteronism were cured by adrenalectomy. Replication identified two more APAs with each variant (total, n = 6). The most upregulated gene (10- to 25-fold) in human adrenocortical H295R cells transduced with the mutations (compared to wildtype) was CYP11B2 (aldosterone synthase), and biological rhythms were the most differentially expressed process. CADM1 knockdown or mutation inhibited gap junction (GJ)-permeable dye transfer. GJ blockade by Gap27 increased CYP11B2 similarly to CADM1 mutation. Human adrenal zona glomerulosa (ZG) expression of GJA1 (the main GJ protein) was patchy, and annular GJs (sequelae of GJ communication) were less prominent in CYP11B2-positive micronodules than adjacent ZG. Somatic mutations of CADM1 cause reversible hypertension and reveal a role for GJ communication in suppressing physiological aldosterone production.

Effectiveness and Safety of a Mixture of Nobiletin and Tangeretin in Nocturia Patients: A Randomized, Placebo-Controlled, Double-Blind, Crossover Study

Nobiletin and tangeretin (NoT) are flavonoids derived from the peel of Citrus depressa, and they have been found to modulate circadian rhythms. Because nocturia can be considered a circadian rhythm disorder, we investigated the efficacy of NoT for treating nocturia. A randomized, placebo-controlled, double-blind, crossover study was conducted. The trial was registered with the Japan Registry of Clinical Trials (jRCTs051180071). Nocturia patients aged ≥50 years who presented nocturia more than 2 times on a frequency-volume chart were recruited. Participants received NoT or a placebo (50 mg once daily for 6 weeks), followed by a washout period of ≥2 weeks. The placebo and NoT conditions were then switched. Changes in nocturnal bladder capacity (NBC) were the primary endpoint, and changes in nighttime frequency and nocturnal polyuria index (NPi) were secondary endpoints. Forty patients (13 women) with an average age of 73.5 years were recruited for the study. Thirty-six completed the study, while four withdrew. No adverse events directly related to NoT were observed. NoT had little effect on NBC compared with the placebo. In contrast, NoT significantly changed nighttime frequency by -0.5 voids compared with the placebo (p = 0.040). The change in NPi from baseline to the end of NoT was significant (-2.8%, p = 0.048). In conclusion, NoT showed little change in NBC but resulted in decreased nighttime frequency with a tendency toward reduced NPi.

Mid-Point of the Active Phase Is Better to Achieve the Natriuretic Effect of Acute Salt Load in Mice

Excess sodium intake and insufficient potassium intake are a prominent global issue because of their influence on high blood pressure. Supplementation of potassium induces kaliuresis and natriuresis, which partially explains its antihypertensive effect. Balancing of minerals takes place in the kidney and is controlled by the circadian clock; in fact, various renal functions exhibit circadian rhythms. In our previous research, higher intake of potassium at lunch time was negatively associated with blood pressure, suggesting the importance of timing for sodium and potassium intake. However, the effects of intake timing on urinary excretion remain unclear. In this study, we investigated the effect of 24 h urinary sodium and potassium excretion after acute sodium and potassium load with different timings in mice. Compared to other timings, the middle of the active phase resulted in higher urinary sodium and potassium excretion. In Clock mutant mice, in which the circadian clock is genetically disrupted, urinary excretion differences from intake timings were not observed. Restricted feeding during the inactive phase reversed the excretion timing difference, suggesting that a feeding-induced signal may cause this timing difference. Our results indicate that salt intake timing is important for urinary sodium and potassium excretion and provide new perspectives regarding hypertension prevention.

Role of circadian rhythms and melatonin in bladder function in heath and diseases

The circadian system modulates all visceral organ physiological processes including urine storage and voiding. The "master clock" of the circadian system lies within suprachiasmatic nucleus of the hypothalamus while "peripheral clocks" are found in most peripheral tissue and organs, including the urinary bladder. Disruptions of circadian rhythms can cause organ malfunction and disorder or exacerbate pre-existing ones. It has been suggested that nocturia, which develops mostly in the elderly, could be a circadian-related disorder of the bladder. In the bladder, many types of gap junctions and ion channels in the detrusor, urothelium and sensory nerves are likely under strict local peripheral circadian control. The pineal hormone, melatonin, is a circadian rhythm synchroniser capable of controlling a variety of physiological processes in the body. Melatonin predominantly acts via the melatonin 1 and melatonin 2 G-protein coupled receptors expressed in the central nervous system, and many peripheral organs and tissues. Melatonin could be beneficial in the treatment of nocturia and other common bladder disorders. The ameliorating action of melatonin on bladder function is likely due to multiple mechanisms which include central effects on voiding and peripheral effects on the detrusor and bladder afferents. More studies are warranted to determine the precise mechanisms of circadian rhythm coordination of the bladder function and melatonin influences on the bladder in health and diseases.

Real-Time Void Spot Assay

Normal voiding behavior is the result of the coordinated function of the bladder, the urethra, and the urethral sphincters under the proper control of the nervous system. To study voluntary voiding behavior in mouse models, researchers have developed the void spot assay (VSA), a method that measures the number and area of urine spots deposited on a filter paper lining the floor of an animal's cage. Although technically simple and inexpensive, this assay has limitations when used as an end-point assay, including a lack of temporal resolution of voiding events and difficulties quantifying overlapping urine spots. To overcome these limitations, we developed a video-monitored VSA, which we call real-time VSA (RT-VSA), and which allows us to determine voiding frequency, assess voided volume and voiding patterns, and make measurements over 6 h time windows during both the dark and light phases of the day. The method described in this report can be applied to a wide variety of mouse-based studies that explore the physiological and neurobehavioral aspects of voluntary micturition in health and disease states.

Sex Inclusion in Transcriptome Studies of Daily Rhythms

Biomedical research on mammals has traditionally neglected females, raising the concern that some scientific findings may generalize poorly to half the population. Although this lack of sex inclusion has been broadly documented, its extent within circadian genomics remains undescribed. To address this gap, we examined sex inclusion practices in a comprehensive collection of publicly available transcriptome studies on daily rhythms. Among 148 studies having samples from mammals in vivo, we found strong underrepresentation of females across organisms and tissues. Overall, only 23 of 123 studies in mice, 0 of 10 studies in rats, and 9 of 15 studies in humans included samples from females. In addition, studies having samples from both sexes tended to have more samples from males than from females. These trends appear to have changed little over time, including since 2016, when the US National Institutes of Health began requiring investigators to consider sex as a biological variable. Our findings highlight an opportunity to dramatically improve representation of females in circadian research and to explore sex differences in daily rhythms at the genome level.

Glucocorticoids coordinate the bladder peripheral clock and diurnal micturition pattern in mice

Peripheral clocks function to regulate each organ and are synchronized though various molecular and behavioral signals. However, signals that entrain the bladder clock remain elusive. Here, we show that glucocorticoids are a key cue for the bladder clock in vitro and in vivo. A pBmal1-dLuc human urothelial cell-line showed significant shifts in gene expression after cortisol treatment. In vivo, rhythmic bladder clock gene expression was unchanged by bilateral adrenalectomy but shifted 4 h forward by corticosterone administration at the inactive phase. Moreover, the bladder clock shifted 8-12 h in mice that underwent both bilateral adrenalectomy and corticosterone administration at the inactive phase. These mice showed decreases in the diurnal rhythm of volume voided per micturition, while maintaining diurnal activity rhythms. These results indicate that the diurnal rhythm of glucocorticoid signaling is a zeitgeber that overcomes other bladder clock entrainment factors and coordinates the diurnal rhythm of volume voided per micturition.

Bladder dysfunction in experimental autoimmune encephalomyelitis reflects clinical severity: A pilot study

Multiple sclerosis (MS) is commonly associated with bladder dysfunction resulting in a progressive loss of voluntary control for urination over time. Here, we used the voided stain on paper (VSOP) method to investigate bladder function in the experimental autoimmune encephalomyelitis (EAE) mouse model of MS. Using the VSOP test, we show that bladder dysfunction reflects pro-inflammatory processes of EAE and severity of clinical EAE symptoms, as characterized by increased urine voided volume per micturition (UVVM) on post-induction day 7 and decreased UVVM on post-induction day 14. The UVVM was closely related to a clinical disease index of EAE symptoms and plasma granulocyte-macrophage colony-stimulating factor (GM-CSF) cytokine levels. UVVM was also sensitive to early life stress caused by animal transportation, which diminished UVVM at the peak of symptoms on post-induction day 14 in EAE mice. The results indicate that symptoms and progression of EAE can be reliably measured by VSOP as a non-motor function assessment.

Melatonin inhibits muscular-mucosal stretch-sensitive bladder afferents via the MT2 receptors

Melatonin is a circadian rhythm regulator capable of controlling a variety of physiological processes in the body. It predominantly acts via the melatonin 1 (MT1) and MT2 receptors expressed in the CNS neurons and peripheral organs and tissues. Melatonin can modulate urinary bladder function, however, to date it is not known if melatonin can regulate activity of sensory neurons innervating the bladder. Bladder afferents play an important role in urine storage and voiding. Therefore, this study aims to determine if melatonin can regulate mechanosensitivity of 2 major classes of sensory neurons in the guinea pig bladder: stretch-insensitive mucosal and low threshold stretch-sensitive muscular-mucosal afferents. The effects of melatonin on the mechanosensitivity of mucosal and muscular-mucosal afferents were measured ex vivo using single unit extracellular recording. Melatonin did not affect the responses of mucosal afferents to stroking of their receptive fields but did concentration-dependently, significantly inhibit 69% of muscular-mucosal afferents responses to stroking and bladder stretch. This inhibitory effect was not affected by the MT1 receptor antagonist, S26131 but was blocked by the selective MT2 receptor antagonists, K-185 and 4-P-PDOT. Forskolin significantly potentiated the responses of muscular-mucosal afferents to stroking and stretch, which were prevented by melatonin. These findings demonstrate a direct inhibitory effect of melatonin on the mechanosensitivity of low threshold stretch-sensitive muscular-mucosal bladder afferents acting via MT2 receptors, which is independent from its action on detrusor muscle. This may have important clinical implications for the treatment of many common bladder disorders including nocturia.

Reduced salt intake partially restores the circadian rhythm of bladder clock genes in Dahl salt-sensitive rats

AIMS

To examine the circadian expression changes in bladder clock genes in Dahl salt-sensitive rats following high salt intake.

MAIN METHODS

Eighteen rats were divided into three groups: the high-salt diet group (HS group), the normal-salt diet group (NS group), and the salt-load interruption group (from a 4 % salt diet to a normal diet; salt-load interruption group [SI group]). Each rat was placed in an individual metabolic cage for 24 h twice weekly. Water intake, urine production, voiding frequency, and voided volume per micturition were recorded. Furthermore, 108 control rats were prepared. Bladders were harvested every 4 h at six time points. Furthermore, the mRNA expression of clock genes and mechanosensors was analyzed.

KEY FINDINGS

In the HS group, the bladder clock genes showed lower mRNA levels than in the NS group. The amplitude of circadian expression changes in bladder clock genes in the HS group was lower than that in the NS group. However, after changing from a 4 % salt diet to a normal diet, the waveforms of the clock gene expression in the SI group were closer to those of the NS group. The 24-hour water intake and urinary volume of the SI group decreased to levels comparable to those of the NS group.

SIGNIFICANCE

Reduced salt intake partially restored the circadian rhythms of bladder clock genes.

DNA Methylation-Related circRNA_0116449 Is Involved in Lipid Peroxidation in Traumatic Brain Injury

Circular ribonucleic acid (circRNA) has a critical effect in central nervous diseases; however, the exact role of circRNAs in human traumatic brain injury (TBI) remains elusive. Epigenetic modifications, such as DNA methylation, can modify the mRNA level of genes without changing their related DNA sequence in response to brain insults. We hypothesized that DNA methylation-related circRNAs may be implicated in the mechanisms of TBI. The methylation-related circ_0116449 was identified from differential methylation positions and shown to reduce the neuronal loss and lipid markers. Mechanical study indicated that circ_0116449 functions as a miR-142-3p sponge and increases the expression of its target gene: NR1D2, together with NR1D1 and RORA to suppress lipid peroxidation both in vitro and in vivo. Our study suggests that DNA methylation-related circ_0116449 may be a novel target for regulating lipid metabolism in TBI.

Timing is everything: impact of development, ageing and circadian rhythm on macrophage functions in urinary tract infections

The bladder supports a diversity of macrophage populations with functional roles related to homeostasis and host defense, including clearance of cell debris from tissue, immune surveillance, and inflammatory responses. This review examines these roles with particular attention given to macrophage origins, differentiation, recruitment, and engagement in host defense against urinary tract infections (UTIs), where these cells recognize uropathogens through a combination of receptor-mediated responses. Time is an important variable that is often overlooked in many clinical and biological studies, including in relation to macrophages and UTIs. Given that ageing is a significant factor in urinary tract infection pathogenesis and macrophages have been shown to harbor their own circadian system, this review also explores the influence of age on macrophage functions and the role of diurnal variations in macrophage functions in host defense and inflammation during UTIs. We provide a conceptual framework for future studies that address these key knowledge gaps.

Piezo channels in the urinary system

The Piezo channel family, including Piezo1 and Piezo2, includes essential mechanosensitive transduction molecules in mammals. Functioning in the conversion of mechanical signals to biological signals to regulate a plethora of physiological processes, Piezo channels, which have a unique homotrimeric three-blade propeller-shaped structure, utilize a cap-motion and plug-and-latch mechanism to gate their ion-conducting pathways. Piezo channels have a wide range of biological roles in various human systems, both in vitro and in vivo. Currently, there is a lack of comprehensive understanding of their antagonists and agonists, and therefore further investigation is needed. Remarkably, increasingly compelling evidence demonstrates that Piezo channel function in the urinary system is important. This review article systematically summarizes the existing evidence of the importance of Piezo channels, including protein structure, mechanogating mechanisms, and pharmacological characteristics, with a particular focus on their physiological and pathophysiological roles in the urinary system. Collectively, this review aims to provide a direction for future clinical applications in urinary system diseases.

Flavonoid Nobiletin Attenuates Cyclophosphamide-Induced Cystitis in Mice through Mechanisms That Involve Inhibition of IL-1β Induced Connexin 43 Upregulation and Gap Junction Communication in Urothelial Cells

Bladder inflammatory diseases cause various urinary symptoms, such as urinary frequency and painful urination, that impair quality of life. In this study, we used a mouse model of cyclophosphamide (CYP)-induced bladder inflammation and immortalized human urothelial (TRT-HU1) cells to explore the preventive potential of nobiletin (NOB), a polymethoxylated flavone enriched in citrus fruit peel, and investigate its mechanism of action in the bladder. Prophylaxis with PMF90 (60% NOB) attenuated the development of bladder inflammation and urinary symptoms in CYP-treated mice. PMF90 also reduced the upregulation of connexin 43 (Cx43), a major component of gap junction channels, in the bladder mucosa of CYP-treated mice. Stimulation of TRT-HU1 cells with the pro-inflammatory cytokine IL-1β increased Cx43 mRNA and protein expression and enhanced gap junction coupling-responses that were prevented by pre-treatment with NOB. In urothelium-specific Cx43 knockout (uCx43KO) mice, macroscopic signs of bladder inflammation and changes in voiding behavior induced by CYP treatment were significantly attenuated when compared to controls. These findings indicate the participation of urothelial Cx43 in the development of bladder inflammation and urinary symptoms in CYP-treated mice and provide pre-clinical evidence for the preventive potential of NOB through its anti-inflammatory effects on IL-1β signaling and urothelial Cx43 expression.

Dietary salt with nitric oxide deficiency induces nocturnal polyuria in mice via hyperactivation of intrarenal angiotensin II-SPAK-NCC pathway

Nocturnal polyuria is the most frequent cause of nocturia, a common disease associated with a compromised quality of life and increased mortality. Its pathogenesis is complex, and the detailed underlying mechanism remains unknown. Herein, we report that concomitant intake of a high-salt diet and reduced nitric oxide (NO) production achieved through N^ω-Nitro-L-arginine methyl ester hydrochloride (L-NAME) administration in mice resulted in nocturnal polyuria recapitulating the clinical features in humans. High salt intake under reduced NO production overactivated the angiotensin II-SPAK (STE20/SPS1-related proline–alanine-rich protein kinase)-NCC (sodium chloride co-transporter) pathway in the kidney, resulting in the insufficient excretion of sodium during the day and its excessive excretion at night. Excessive Na excretion at night in turn leads to nocturnal polyuria due to osmotic diuresis. Our study identified a central role for the intrarenal angiotensin II-SPAK-NCC pathway in the pathophysiology of nocturnal polyuria, highlighting its potential as a promising therapeutic target.

This study reports a mouse model of nocturnal polyuria - increased urine production at night that causes compromised quality of life and may impact mortality in older people. The authors identify a molecular pathway in the kidney that could prove to be a promising drug target for nocturnal polyuria.

Effects of fatty acid metabolites on nocturia

Dysregulation of circadian rhythm can cause nocturia. Levels of fatty acid metabolites, such as palmitoylethanolamide (PEA), 9-hydroxy-10E,12Z-octadecadienoic acid (9-HODE), and 4-hydroxy-5E,7Z,10Z,13Z,16Z,19Z-docosahexaenoic acid (4-HDoHE), are higher in the serum of patients with nocturia; however, the reason remains unknown. Here, we investigated the circadian rhythm of fatty acid metabolites and their effect on voiding in mice. WT and Clock mutant (ClockΔ19/Δ19) mice, a model for nocturia with circadian rhythm disorder, were used. Levels of serum PEA, 9-HODE, and 4-HDoHEl were measured every 8 h using LC/MS. Voiding pattern was recorded using metabolic cages after administration of PEA, 9-HODE, and 4-HDoHE to WT mice. Levels of serum PEA and 9-HODE fluctuated with circadian rhythm in WT mice, which were lower during the light phase. In contrast, circadian PEA and 9-HODE level deteriorated or retreated in ClockΔ19/Δ19 mice. Levels of serum PEA, 9-HODE, and 4-HDoHE were higher in ClockΔ19/Δ19 than in WT mice. Voiding frequency increased in PEA- and 4-HDoHE-administered mice. Bladder capacity decreased in PEA-administered mice. The changes of these bladder functions in mice were similar to those in elderly humans with nocturia. These findings highlighted the novel effect of lipids on the pathology of nocturia. These may be used for development of biomarkers and better therapies for nocturia.

Insights into the development of a new index, vesical adaptation response to diuresis, for understanding lower urinary tract dysfunction

OBJECTIVES

To clarify how vesical adaptation response, the homeostatic system that constantly changes voided volume to adapt to diuresis, is involved in male lower urinary tract symptoms and bladder storage function.

METHODS

We included male patients older than 65 years with lower urinary tract symptoms. Vesical adaptation response to diuresis was defined as a positive correlation between urine output rate and voided volume on 3-day sensory-related frequency volume charts. Patients were divided into two groups according to the presence or absence of vesical adaptation response to diuresis, and characteristics were compared between groups.

RESULTS

Ninety-four male patients were finally analyzed. Vesical adaptation response to diuresis was found in 48 patients (51%) and was lacking in 46 patients (49%). Patients without vesical adaptation response to diuresis were significantly more often diagnosed with overactive bladder (P = 0.04). After adjusting for confounders, absence of vesical adaptation response to diuresis was significantly associated with overactive bladder (adjusted odds ratio 3.76, 95% confidence interval 1.34-10.55; P = 0.01) and benign prostatic enlargement (adjusted odds ratio 1.04, 95% confidence interval 1.01-1.07; P = 0.02).

CONCLUSIONS

The absence of vesical adaptation response to diuresis, characterized by decreased voided volume during a diuretic phase, can be interpreted as a form of bladder storage dysfunction. Assessment of vesical adaptation response to diuresis may provide a new index of bladder storage function and contribute to a better understanding of the pathophysiology underlying bladder storage dysfunction in patients with lower urinary tract symptoms.

The effects of choreito on a model of nocturnal polyuria using Dahl salt-sensitive rats

OBJECTIVES

This study aimed to determine whether Dahl salt-sensitive rats fed a high-salt diet would show features of nocturia due to nocturnal polyuria and to examine the efficacy of choreito (CRT) on nocturnal polyuria.

METHODS

Dahl salt-sensitive rats were divided into three groups. Group A was fed a 4% salt diet, group B a 2% salt diet, and group C a normal 0.3% salt diet. In groups α and β, other rats were further divided into two groups: The rats in group α were fed a 2% salt plus 3% CRT diet, and those in group β, were fed a 2% salt diet. Each rat was placed in an individual metabolic cage for 24 hours every week for 6 weeks. Water intake, urine production, voiding frequency, and voided volume per micturition were recorded.

RESULTS

The systolic blood pressure increased in the group fed a 4% salt diet compared to groups fed with a 2% and 0.3% salt diet. The urinary volume was higher in the groups fed with 4% and 2% salt than in the group fed with 0.3% salt. Further, water intake in the group fed a 2% salt plus 3% CRT diet was significantly lower than that in the group fed with a 2% salt diet.

CONCLUSIONS

Dahl salt-sensitive rats fed a 2% salt diet were candidates for a model of nocturnal polyuria. Using this model, we suggest that CRT reduces water intake in the active phase and contributes to water restriction in the treatment of nocturnal polyuria.

Time-of-day dependent changes in guinea pig bladder afferent mechano-sensitivity

The voiding of urine has a clear circadian rhythm with increased voiding during active phases and decreased voiding during inactive phases. Bladder spinal afferents play a key role in the regulation of bladder storage and voiding, but it is unknown whether they exhibit themselves a potential circadian rhythm. Therefore, this study aimed to determine the mechano- and chemo- sensitivity of three major bladder afferent classes at two opposite day-night time points. Adult female guinea pigs underwent conscious voiding monitoring and bladder ex vivo single unit extracellular afferent recordings at 0300 h and 1500 h to determine day-night modulation of bladder afferent activity. All guinea pigs voided a higher amount of urine at 1500 h compared to 0300 h. This was due to an increased number of voids at 1500 h. The mechano-sensitivity of low- and high-threshold stretch-sensitive muscular-mucosal bladder afferents to mucosal stroking and stretch was significantly higher at 1500 h compared to 0300 h. Low-threshold stretch-insensitive mucosal afferent sensitivity to stroking was significantly higher at 1500 h compared to 0300 h. Further, the chemosensitivity of mucosal afferents to N-Oleoyl Dopamine (endogenous TRPV1 agonist) was also significantly increased at 1500 h compared to 0300 h. This data indicates that bladder afferents exhibit a significant time-of-day dependent variation in mechano-sensitivity which may influence urine voiding patterns. Further studies across a 24 h period are warranted to reveal potential circadian rhythm modulation of bladder afferent activity.

Physiological rhythms are influenced by photophase wavelength in a nocturnal and a diurnal rodent species from South Africa

The quality and quantity of light changes significantly over the course of the day. The effect of light intensity on physiological and behavioural responses of animals has been well documented, particularly during the scotophase, but the effect of the wavelength of light, particularly during the photophase, less so. We assessed the daily responses in urine production, urinary 6-sulfatoxymelatonin (6-SMT) and glucocorticoid metabolite (uGCM) concentrations in the nocturnal Namaqua rock mouse (Micaelamys namaquensis) and diurnal four striped field mouse (Rhabdomys pumilio) under varying wavelengths of near monochromatic photophase (daytime) lighting. Animals were exposed to a short-wavelength light cycle (SWLC; ∼465-470 nm), a medium-wavelength light cycle (MWLC; ∼515-520 nm) and a long-wavelength light cycle (LWLC; ∼625-630 nm). The SWLC significantly attenuated mean daily urine production rates and the mean daily levels of urinary 6-SMT and of uGCM were inversely correlated with wavelength in both species. The presence of the SWLC greatly augmented overall daily 6-SMT levels, and simultaneously led to the highest uGCM concentrations in both species. In M. namaquensis, the urine production rate and urinary 6-SMT concentrations were significantly higher during the scotophase compared to the photophase under the SWLC and MWLC, whereas the uGCM concentrations were significantly higher during the scotophase under all WLCs. In R. pumilio, the urine production rate and uGCM were significantly higher during the scotophase of the SWLC, not the MWLC and LWLC. Our results illustrate that wavelength in the photophase plays a central role in the entrainment of rhythms in diurnal and nocturnal African rodent species.

Different effects of GsMTx4 on nocturia associated with the circadian clock and Piezo1 expression in mice

OBJECTIVES

Nocturia is a major problem in geriatric patients. Clock genes regulate circadian bladder function and Piezo type mechanosensitive ion channel component 1 (Piezo1) that senses bladder fullness. We utilized WT and Clock mutant (Clock^Δ19/Δ19: nocturia phenotype) mice to determine if the effects of GsMTx4, a Piezo1 inhibitor, is dependent on circadian Piezo1 expression in the bladder.

METHODS

We compared voiding behavior in mice after the administration of vehicle, low dose, or high dose of GsMTx4. Intraperitoneal injections (IP) were performed at Zeitgeber time (ZT) 0, lower Piezo1 expression phase (ZT0-IP) and ZT12, higher Piezo1 expression phase (ZT12-IP). Urine volume (Uvol), voiding frequency (VF), and urine volume per void (Uvol/v) were measured using metabolic cages.

RESULTS

VF decreased at ZT12-IP in WT mice only with high dose of GsMTx4 but showed no effects in Clock^Δ19/Δ19 mice. VF decreased significantly at ZT0-IP in WT mice after both doses, but only decreased after high dose in Clock^Δ19/Δ19 mice. Uvol/v increased in WT mice at ZT0-IP after both doses and at ZT12-IP after high dose. Uvol/v increased in Clock^Δ19/Δ19 mice only at ZT0-IP after high dose. GsMTx4 did not affect Uvol in both mice at ZT12-IP. A decrease in Uvol was observed in both mice at ZT0-IP; however, it was unrelated to GsMTx4-IP.

CONCLUSIONS

The effects of GsMTx4 changed associated with the circadian clock and Piezo1 expression level. The maximum effect occurred during sleep phase in WT. These results may lead to new therapeutic strategies against nocturia.

Urothelium-Specific Deletion of Connexin43 in the Mouse Urinary Bladder Alters Distension-Induced ATP Release and Voiding Behavior

Connexin43 (Cx43), the main gap junction and hemichannel forming protein in the urinary bladder, participates in the regulation of bladder motor and sensory functions and has been reported as an important modulator of day-night variations in functional bladder capacity. However, because Cx43 is expressed throughout the bladder, the actual role played by the detrusor and the urothelial Cx43 is still unknown. For this purpose, we generated urothelium-specific Cx43 knockout (uCx43KO) mice using Cre-LoxP system. We evaluated the day-night micturition pattern and the urothelial Cx43 hemichannel function of the uCx43KO mice by measuring luminal ATP release after bladder distention. In wild-type (WT) mice, distention-induced ATP release was elevated, and functional bladder capacity was decreased in the animals' active phase (nighttime) when Cx43 expression was also high compared to levels measured in the sleep phase (daytime). These day-night differences in urothelial ATP release and functional bladder capacity were attenuated in uCx43KO mice that, in the active phase, displayed lower ATP release and higher functional bladder capacity than WT mice. These findings indicate that urothelial Cx43 mediated ATP signaling and coordination of urothelial activity are essential for proper perception and regulation of responses to bladder distension in the animals' awake, active phase.

Are sham-operated mice a valid comparator in studies using a bladder outlet obstruction model? A pitfall reveals a meaningful insight

OBJECTIVE

To evaluate voiding behavior characteristics in intact and sham mice, and to examine whether intact mice show changes in "normal" micturition with aging.

METHODS

A total of 72 8-week-old mice were divided into two groups - intact and sham - and the latter group was subjected to a sham of partial bladder outlet obstruction surgery. Urination frequency was evaluated (through metabolic cages) at 1, 2, 3, 6 and 12 months after the surgery (or at the equivalent time points for the intact mice). To address possible mechanisms for aging and surgical effects on urinary behavior, quantitative real-time polymerase chain reaction assays were carried out. Primary data were evaluated using scatter plots and descriptive statistics.

RESULTS

In sham mice, urination frequency showed strong variation at the earlier post-surgical time points (especially at 1 month), with variation decreasing with time. Quantitative real-time polymerase chain reaction showed that the serotonin 2C receptor-encoding mRNA accumulated to >28-fold higher levels at 24 months compared with 3 months in intact mice. A major limitation of the quantitative real-time polymerase chain reaction experiments was that we did not separate whole bladder into muscle and mucosa.

CONCLUSIONS

Although a sham operation is typically used in partial bladder outlet obstruction experiments to provide control animals, the sham group might itself show increased variation in micturition frequency at early times after surgery, compared with intact animals.

Medical history of nocturnal enuresis during school age is an independent risk factor for nocturia in adults: The Nagahama study

AIM

To evaluate the relationship between nocturia and medical history of nocturnal enuresis: two conditions where diurnal urination rhythm is disturbed.

METHODS

The Nagahama study is a longitudinal population-based health survey involving people aged 30-75 years in Nagahama city, Japan. Our analysis included 5,402 participants who completed enuresis and International Prostate Symptom Score questionnaires. Associations between nocturnal enuresis and nocturia were evaluated cross-sectionally and longitudinally with three models: (1) univariate analysis; (2) adjusted for basic characteristics (e.g., age, sex, body mass index, activity, alcohol, and smoking); and (3) adjusted for basic and clinical variables (e.g., hyperglycemia, hyperlipidemia, hypertension, renal insufficiency, insomnia, obstructive sleep apnea, and mental health).

RESULTS

In total, 1,613 participants (29.9%) had a medical history of enuresis. The mean night-time frequency was 0.73 at baseline and 0.85 at the 5-year follow-up. The cross-sectional analysis showed participants with a medical history of enuresis had night-time frequency more often than those without this history (0.84 vs. 0.68, p < .0001). Significant differences were observed in Models 2 (p < .0001) and 3 (p < .0001). The longitudinal analysis showed nocturia progression was significantly related to a history of enuresis, with odds ratios of 1.32 (p < .0001) in Model 1, 1.21 (p < .01) in Model 2, and 1.22 (p < .01) in Model 3.

CONCLUSIONS

Medical history of enuresis during school age was significantly related to nocturia in adulthood in the cross-sectional analysis, and to progression to nocturia in the longitudinal analysis. These two conditions may possess a common causative association.

The Urothelium: Life in a Liquid Environment

The urothelium, which lines the renal pelvis, ureters, urinary bladder, and proximal urethra, forms a high-resistance but adaptable barrier that surveils its mechanochemical environment and communicates changes to underlying tissues including afferent nerve fibers and the smooth muscle. The goal of this review is to summarize new insights into urothelial biology and function that have occurred in the past decade. After familiarizing the reader with key aspects of urothelial histology, we describe new insights into urothelial development and regeneration. This is followed by an extended discussion of urothelial barrier function, including information about the roles of the glycocalyx, ion and water transport, tight junctions, and the cellular and tissue shape changes and other adaptations that accompany expansion and contraction of the lower urinary tract. We also explore evidence that the urothelium can alter the water and solute composition of urine during normal physiology and in response to overdistension. We complete the review by providing an overview of our current knowledge about the urothelial environment, discussing the sensor and transducer functions of the urothelium, exploring the role of circadian rhythms in urothelial gene expression, and describing novel research tools that are likely to further advance our understanding of urothelial biology.

Animal Model for Lower Urinary Tract Dysfunction in Parkinson's Disease

Although Parkinson's disease (PD) is characterized by the loss of dopaminergic neurons in the substantia nigra and subsequent motor symptoms, various non-motor symptoms often precede these other symptoms. While motor symptoms are certainly burdensome, a wide range of non-motor symptoms have emerged as the key determinant of the quality of life in PD patients. The prevalence of lower urinary tract symptoms differs according to the study, with ranges between 27% and 63.9%. These can be influenced by the stage of disease, the presence of lower urinary tract-related comorbidities, and parallels with other manifestations of autonomic dysfunction. Animal models can provide a platform for investigating the mechanisms of PD-related dysfunction and for the assessment of novel treatment strategies. Animal research efforts have been primarily focused on PD motor signs and symptoms. However, the etiology of lower urinary tract dysfunction in PD has yet to be definitively clarified. Several animal PD models are available, each of which has a different effect on the autonomic nervous system. In this article, we review the various lower urinary tract dysfunction animal PD models. We additionally discuss techniques for determining the appropriate model for evaluating the development of lower urinary tract dysfunction treatments.

Chronoradiation Therapy for Prostate Cancer: Morning Proton Beam Therapy Ameliorates Worsening Lower Urinary Tract Symptoms

Background and Purpose: Worsening lower urinary tract symptoms (LUTS) are a frequent adverse event following proton beam therapy (PBT) for localized prostate cancer. We investigated the differences in worsening LUTS among patients who received PBT at different times of day. Participants and Methods: Among 173 patients who underwent PBT for prostate cancer, 168 patients (median age 68.5 years) completed international prostate symptom score (IPSS) questionnaires and were included. Changes in the IPSS from baseline to the end of PBT were assessed by multiple linear regression analysis for age, National Comprehensive Cancer Network risk classification, androgen deprivation therapy, fractional PBT dose, clinical target volume, severity of IPSS, diabetes, LUTS medication use before PBT, anti-coagulant therapy and radiation time of day (morning (08:30–10:30), around noon (10:31–14:30), and late afternoon (14:31–16:30)). Results: IPSS total score and IPSS-Quality of Life (QoL) score (12 patients were excluded due to missing IPSS-QoL score) increased from eight to 14.9 (p < 0.0001) and from two to four (p < 0.0001), respectively. Time of day (morning) was the only determinant for worsening LUTS (β = −0.24, p < 0.01), voiding subscore (β = −0.22, p < 0.05) and IPSS-QoL (β = −0.27, p < 0.005), and was a determinant in item four (urgency) (β = −0.28, p < 0.005) with age (β = 0.19, p < 0.05). Conclusions: Morning PBT for localized prostate cancer significantly ameliorated worsening LUTS and improved QoL compared with treatment around noon or late afternoon. Chronoradiation therapy for localized prostate cancer may be effective and further research to elucidate the underlying mechanism is warranted.

Bladder outlet obstruction disrupts circadian bladder function in mice

The circadian clock programs daily rhythms and coordinates multiple behavioural processes, including micturition. Partial bladder outlet obstruction (pBOO) in mice produces hyperactive voiding. However, long-term effects of pBOO on bladder function have not been clarified. In this study, we investigated micturition under conditions of impaired circadian bladder function by inducing long-term pBOO by tying the proximal urethra. Micturition behavior was evaluated at 1, 3, 6 and 12 months after surgery. We used automated voided stain on paper method for a precise micturition recording for mice. And quantitative assessment of gene expression was performed at 24 months after pBOO surgery using qRT-PCR procedure. The micturition frequencies in the pBOO group were significantly decreased at 3, 6, and 12 months compared to those at 1 month after operation in the same group (p < 0.05). Body weight of pBOO mice was significantly increased compared to sham operated mice at 12 months. The expression level of mRNA was exhibited a 3.4-fold nominal increased for a 5-HT2B receptor in the pBOO group compared to the sham group. The current study found that long-term pBOO led to disruption of the circadian bladder function (the day/night cycle) in mice, similar to those observed in human as nocturia. This disruption is possible involvement of the gain of body weight and/or serotonergic alteration after pBOO.

The Role of Purinergic Receptors in the Circadian System

The circadian system is an internal time-keeping system that synchronizes the behavior and physiology of an organism to the 24 h solar day. The master circadian clock, the suprachiasmatic nucleus (SCN), resides in the hypothalamus. It receives information about the environmental light/dark conditions through the eyes and orchestrates peripheral oscillators. Purinergic signaling is mediated by extracellular purines and pyrimidines that bind to purinergic receptors and regulate multiple body functions. In this review, we highlight the interaction between the circadian system and purinergic signaling to provide a better understanding of rhythmic body functions under physiological and pathological conditions.

Circadian clock and cancer: From a viewpoint of cellular differentiation

The circadian clock controls and adapts diverse physiological and behavioral processes according to Earth's 24-h cycle of environmental changes. The master pacemaker of the mammalian circadian clock resides in the hypothalamic suprachiasmatic nucleus, but almost all cells throughout the body show circadian oscillations in gene expression patterns and associated functions. Recent studies have shown that the circadian clock gradually develops during embryogenesis. Embryonic stem cells and induced pluripotent stem cells do not show circadian oscillations of gene expression, but gradually develop circadian clock oscillation during differentiation; thus, the developmental program of circadian clock emergence appears closely associated with cellular differentiation. Like embryonic stem cells, certain cancer cell types also lack the circadian clock. Given this similarity between embryonic stem cells and cancer cells, interest is growing in the contributions of circadian clock dysfunction to dedifferentiation and cancer development. In this review, we summarize recent advances in our understanding of circadian clock emergence during ontogenesis, and discuss possible associations with cellular differentiation and carcinogenesis. Considering the multiple physiological functions of circadian rhythms, circadian abnormalities might contribute to a host of diseases, including cancer. Insights on circadian function could lead to the identification of biomarkers for cancer diagnosis and prognosis, as well as novel targets for treatment.

Persistent myopathy despite release of partial obstruction: in vivo reversal of dysfunction and transcriptional responses using rapamycin

Current and potential medical therapy for obstruction-induced myopathic bladder dysfunction (from benign prostatic hyperplasia or posterior urethral valves) focuses on symptoms. The persistent tissue pathology and dysfunction after release of obstruction is often deemed irreversible without any systematic therapeutic approaches. As rapamycin can attenuate bladder smooth muscle hypertrophy and dysfunction during the genesis of partial obstruction in vivo, we tested whether rapamycin could improve persistent function after release of obstruction (de-obstruction or REL). Female Sprague-Dawley rat bladders were partially obstructed (PBO) by suturing around both the urethra and a para-urethral steel rod, then removing the rod. One day prior to release of obstruction (preREL), voiding parameters and residual urine volume of preREL+future rapa, preREL+future veh groups were recorded. Release of obstruction (REL) was performed by suture removal following 6 weeks of PBO. For 4 more weeks after the de-obstruction, REL animals were randomized to rapamycin (REL+rapa) or vehicle (REL+veh). PBO for 6 weeks were used as positive controls. In shams, the urethra was exposed, but no suture tied. Voiding parameters and residual urine volume were measured prior to sacrifice of sham and REL+veh or REL+rapa, and PBO. Rapamycin efficacy was tested by pair-wise comparison of changes in individual voiding data from preREL+future veh or preREL+future rapa versus REL+veh or REL+rapa, respectively, as well as by comparisons of REL+veh to REL+rapa groups. Bladders were weighed and processed for a high-throughput QPCR array, and histopathology. Bladder/body mass ratios with PBO increased significantly and remained higher in the release phase in REL+veh animals. REL+rapa versus REL+veh improved residual volumes and micturition fractions toward sham levels. Three genes encoding extracellular proteins, BMP2, SOD3, and IGFBP7, correlated with functional improvement by Pearson's correlations. The promoters of these genes showed enrichment for several motifs including circadian E-boxes. While obstruction and REL augmented CLOCK and NPAS2 expression above sham levels, rapamycin treatment during release significantly blocked their expression. This experimental design of pharmaco-intervention during the de-obstruction phase revealed a novel pathway dysregulated during the clinically relevant treatment phase of obstructive bladder myopathy.

Influence of Circadian Disruption Associated With Artificial Light at Night on Micturition Patterns in Shift Workers

Shift workers often experience problems associated with circadian disruption associated with artificial light at night and nocturia is commonly noted in night-shift workers. Nocturia associated with circadian disruption is due to increased urine production of the kidney and decreased storage function of the bladder. A recent discovery of peripheral clock genes in the bladder and their role in contractile property of the bladder support that micturition is closely related to the circadian rhythm. Moreover, there are clinical studies showed that shift workers more often experienced nocturia due to circadian disruption. However, comparing with other health problems, concerns on nocturia and voiding dysfunction associated with circadian disruption are insufficient. Therefore, further studies about voiding dysfunction associated with the circadian disruption in shift workers are necessary.

Micturition video thermography in awake, behaving mice

BACKGROUND

Our understanding of the neural circuits controlling micturition and continence is constrained by a paucity of techniques for measuring voiding in awake, behaving mice.

NEW METHOD

To facilitate progress in this area, we developed a new, non-invasive assay, micturition video thermography (MVT), using a down-facing thermal camera above mice on a filter paper floor.

RESULTS

Most C57B6/J mice void infrequently, with a stereotyped behavioral sequence, and usually in a corner. The timing of each void is indicated by the warm thermal contrast of freshly voided urine. Over the following 10-15 min, urine cools to ∼3 °C below the ambient temperature and spreads radially in the filter paper. By measuring the area of cool contrast comprising this "thermal void spot," we can derive the initially voided volume. Thermal videos also reveal mouse behaviors including a home-corner preference apart from void spots, and a stereotyped, seconds-long pause while voiding.

COMPARISON WITH EXISTING METHODS AND CONCLUSIONS

MVT is a robust, non-invasive method for measuring the timing, volume, and location of voiding. It improves on an existing technique, the void spot assay, by adding timing information, and unlike the cystometrogram preparation, MVT does not require surgical catheterization. Combining MVT with current neuroscience techniques will improve our understanding of the neural circuits that control continence, which is important for addressing the growing number of patients with urinary incontinence as the population ages.

CoQ10 ameliorates monosodium glutamate-induced alteration in detrusor activity and responsiveness in rats via anti-inflammatory, anti-oxidant and channel inhibiting mechanisms

Background

Competent detrusor muscles with coordinated contraction and relaxation are crucial for normal urinary bladder storage and emptying functions. Hence, detrusor instability, and subsequently bladder overactivity, may lead to undesirable outcomes including incontinence. Multiple mechanisms may underlie the pathogenesis of detrusor overactivity including inflammation and oxidative stress. Herein, we tested the possibility that CoQ10 may have a potential therapeutic role in detrusor overactivity.

Methods

Forty adult male Wistar albino rats weighing 100-150 g were used in the present study. Rats were divided (10/group) into control (receiving vehicles), monosodium glutamate (MSG)-treated (receiving 5 mg/kg MSG daily for 15 consecutive days), MSG + OO-treated (receiving concomitantly 5 mg/kg MSG and olive oil for 15 consecutive days), MSG + CoQ10-treated (receiving concomitantly 5 mg/kg MSG and 100 mg/kg CoQ10 daily for 15 consecutive days) groups.

Results

MSG resulted in significant increase in bladder weight and sensitised the bladder smooth muscles to acetylcholine. MSG has also resulted in significant increase in bladder TNF-α, IL-6, malondialdehyde, nerve growth factor and connexion 43, with significant decrease in the antioxidant enzymes superoxide dismutase and catalase. Olive oil had no effect on MSG induced alterations of different parameters. Treatment with CoQ10 has resulted in a significant restoration of all the altered parameters.

Conclusion

Taken together, our results suggest that CoQ10 antagonizes the deleterious effects of MSG on detrusor activity. We propose that CoQ10 could be a therapeutic strategy targeting urinary bladder dysfunction.

Targeting TRP Channels - Valuable Alternatives to Combat Pain, Lower Urinary Tract Disorders, and Type 2 Diabetes?

Transient receptor potential (TRP) channels are a family of functionally diverse and widely expressed cation channels involved in a variety of cell signaling and sensory pathways. Research in the last two decades has not only shed light on the physiological roles of the 28 mammalian TRP channels, but also revealed the involvement of specific TRP channels in a plethora of inherited and acquired human diseases. Considering the historical successes of other types of ion channels as therapeutic drug targets, small molecules that target specific TRP channels hold promise as treatments for a variety of human conditions. In recent research, important new findings have highlighted the central role of TRP channels in chronic pain, lower urinary tract disorders, and type 2 diabetes, conditions with an unmet medical need. Here, we discuss how these advances support the development of TRP-channel-based pharmacotherapies as valuable alternatives to the current mainstays of treatment.

The circadian rhythm of bladder clock genes in the spontaneously hypersensitive rat

Circadian expression rhythms of clock gene products in the bladder are reportedly hindered by clock gene abnormalities. However, the role of clock gene products in various pathological lower urinary tract conditions is unknown. The present study examined the relationship between clock genes and voiding dysfunction in spontaneous hypertensive rats (SHR). The voluntary voiding behavior study using metabolic cages was performed in 18-weeks old male Wistar rats (control group, n = 36) and SHR (SHR group, n = 36) under 12-h light/12-h dark conditions. Bladders were harvested every 4 h at six time points (n = 6 for each time point for each group), and we analyzed the messenger RNA (mRNA) expression of several clock genes: period 2 (Per2), cryptochrome 2 (Cry2), brain and muscle aryl hydrocarbon receptor nuclear translocator-like protein 1 (Bmal1), circadian locomotor output cycles kaput (Clock), nuclear receptor subfamily 1, group D, member 1 (Rev-erbα), mechanosensors: transient receptor potential vanilloid channel 1 (TRPV1), TRPV4, Piezo1, and vesicular nucleotide transporter (VNUT) using real-time polymerase chain reaction. Though 24-h urination frequency for both light and dark periods was significantly higher in the SHR group, urine volume per voiding was significantly lower versus control. In controls, urine volume per voiding was significantly lower during the dark period (active phase) than the light period (rest phase); this parameter did not significantly differ between active and rest phases for SHR. SHR bladders showed significantly higher expression of Cry2 and Clock during the active phase compared to controls. In the SHR group, TRPV1, TRPV4, Piezo1, and VNUT mRNA levels were significantly higher during the active phase compared to the control group. We speculate that Cry2 and Clock may be contributing factors in the decrease of bladder capacity during the active phase in SHR through increase of TRPV1, TRPV4, Piezo1, and VNUT expression, but further research will be necessary to elucidate the precise mechanisms.

Intermittent restraint stress induces circadian misalignment in the mouse bladder, leading to nocturia

Intermittent stress disrupts the circadian rhythm in clock genes such as Per2 only in peripheral organs without any effect on the central circadian clock in the suprachiasmatic nucleus. Here, the effect of restraint stress (RS) on circadian bladder function was investigated based on urination behavior and gene expression rhythms. Furthermore, PF670462 (PF), a Per2 phosphorylation enzyme inhibitor, was administered to investigate the effects on circadian bladder re-alignment after RS. Two-hour RS during the light (sleep) phase was applied to mice (RS mice) for 5 days. The following parameters were then examined: urination behaviors; clock gene expression rhythms and urinary sensory-related molecules such as piezo type mechanosensitive ion channel component 1 (Piezo1), transient receptor potential cation channel subfamily V member 4 (TRPV4), and Connexin26 (Cx26) in the bladder mucosa; Per2 expression in the excised bladder of Per2^luciferase knock-in mice (Per2::luc); in vivo Per2 expression rhythms in the bladder of Per2::luc mice. Control mice did not show altered urination behavior in the light phase, whereas RS mice exhibited a higher voiding frequency and lower bladder capacity. In the bladder mucosa, RS mice also showed abrogated or misaligned Piezo1, TRPV4, Connexin26, and clock gene expression. The rhythmic expression of Per2 was also altered in RS mice both in excised- and in vivo bladder, compared with control mice. After PF administration, voiding frequency was reduced and bladder capacity was increased during the light phase in RS mice; the in vivo Per2 expression rhythm was also fully restored. Therefore, RS can alter circadian gene expression in the bladder during the light phase and might cause nocturia via changes in circadian bladder function due the dysregulation of clock genes. Amending the circadian rhythm therapeutically could be applied for nocturia.

Voided volumes predict degree of partial bladder outlet obstruction in a murine model

The partial bladder outlet obstruction animal model (pBOO) is commonly used as a model for obstructive uropathy. Unfortunately, pBOO demonstrates variable degrees of obstruction requiring bladder weight (BW) or urodynamic studies to determine true obstruction. Our objective is to identify extent of obstruction by correlating early post-operative Void Stains on Paper (VSOP) assays with ultimate BW in mice. pBOO was performed on 32 mice 1- and 4-week VSOPs were quantified for mean voided volume (mVV). At 4 weeks, bladders were harvested and weighed. Correlation was evaluated through bivariate kernel density estimation and a Pearson correlation coefficient (SAS). Single variable histogram of the data established groups based on BWs and mVV. mVV's and bladder weights within group pairings were averaged and plotted to render a non-linear regression model. A significant correlation was found between 1-week mVVs and 4-week BWs upon bivariate analysis with a correlation coefficient of -0.758 (p = 0.0294). A non-linear regression of plotted data defined a statistically significant fit equation correlating 1-week mVV to 4-week BW. We demonstrate a novel method for forecasting degree of obstruction in pBOO based on 1-week post-operative VSOP mVV.