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When bacteria enter the bladder lumen, a first-stage active defensive mechanism flushes them out. Although urinary frequency induced by bacterial cystitis is a well-known defensive response against bacteria, the underlying mechanism remains unclear. In this study, using a mouse model of acute bacterial cystitis, we demonstrate that the bladder urothelium senses luminal extracellular bacterial lipopolysaccharide (LPS) through Toll-like receptor 4 and releases the transmitter ATP. Moreover, analysis of purinergic P2X2 and P2X3 receptor-deficient mice indicated that ATP signaling plays a pivotal role in the LPS-induced activation of L6–S1 spinal neurons through the bladder afferent pathway, resulting in rapid onset of the enhanced micturition reflex. Thus, we revealed a novel defensive mechanism against bacterial infection via an epithelial-neural interaction that induces urinary frequency prior to bacterial clearance by neutrophils of the innate immune system. Our results indicate an important defense role for the bladder urothelium as a chemical-neural transducer, converting bacterial LPS information into neural signaling via an ATP-mediated pathway, with bladder urothelial cells acting as sensory receptor cells.

To determine the pathophysiology of nocturnal polyuria associated with renal dysfunction, patients who underwent laparoscopic nephrectomy were prospectively studied. The diurnal variation in urine volume, osmolality, and salt excretion were measured on preoperative day 2 and postoperative day 7. The factors associated with an increase in the nighttime urine volume rate with decreased renal function were evaluated using multiple linear regression analysis. Forty-nine patients were included. The estimated glomerular filtration rate decreased from 73.3 ± 2.0 to 47.2 ± 1.6 mL/min/1.73 m2 (P < 0.01) and the nighttime urine volume rate increased from 40.6% ± 2.0% to 45.3% ± 1.5% (P = 0.04) with nephrectomy. The nighttime urine osmolality decreased from 273 ± 15 to 212 ± 10 mOsm/kg and the nighttime salt excretion rate increased from 38.7% ± 2.1% to 48.8% ± 1.7% (both P < 0.01) with nephrectomy. Multiple linear regression analysis showed that the increase in the nighttime urine volume rate was strongly affected by the increase in the nighttime salt excretion rate. A decrease in renal function causes an increase in the nighttime urine volume rate, mainly because of an increase in nighttime salt excretion.Trial registration number: UMIN000036760 (University Hospital Medical Information Network Clinical Trials Registry).Date of registration: From 1 June 2019 to 31 October 2020.

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 Nω-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.

Background Varicocoele‐induced male infertility potentially involves oxidative stress. Although varicocoelectomy is recommended for varicocoele patients presenting abnormal semen findings, no pharmacotherapeutic methods currently exist. We have recently developed a silicon‐based agent that produces hydrogen by the reaction with water. Objectives This study aimed to investigate the therapeutic effects of oral administration of a Si‐based agent on varicocoele rat. Materials and methods Twenty‐one rats were divided into four groups: varicocoele + normal diet (n = 5), varicocoele + Si‐based agent‐supplemented diet (n = 6), sham + normal diet (n = 5), and sham + Si‐based agent‐supplemented diet (n = 5). All rats were euthanized four weeks after surgery. Results The mean left epididymal sperm motility was 74.4% in the sham group, 72.3% in the sham + Si group, 57.6% in the varicocoele group, and 66.9% in the varicocoele + Si group. Epididymal sperm motility was significantly lower in the varicocoele group, but was significantly higher upon Si‐based agent ingestion (P < .01). The mean left testicular weight, Johnsen's score, and left epididymal sperm concentration did not differ significantly between groups. The 8‐OHdG concentration and DNA fragmentation rate were significantly increased in the varicocoele group, but were significantly decreased in the Si‐based agent intake group (P < .01). Additionally, the IVF rate was significantly lower in the varicocoele group (26.3%) compared with the sham group (73.4%; P < .01), and was significantly higher in the varicocoele + Si group (51.8%) compared with the varicocoele group (P < .05), indicating that the Si‐based agent improves IVF rates. Discussion and conclusion Oral intake of the silicon‐based agent improves epididymal sperm motility and in vitro fertilization rates through hydrogen production and subsequent reduction of oxidative stress. Considering the lack of effective noninvasive methods, this Si‐based agent is potentially applicable for treating varicocoele‐induced abnormal semen parameters.