Cold Stress and Urinary Frequency

Transient receptor potential ankyrin 1 channels in the bladder mediate low temperature elicited bladder overactivity in rats

AIMS

This study aimed to investigate whether pathways involving transient receptor potential ankyrin 1 (TRPA1) channels in the urinary bladder mediate the bladder overactivity elicited by exposure to a low temperature in rats.

METHODS

At postnatal week 10, female Sprague-Dawley (SD) rats were intraperitoneally injected with the TRPA1 channel antagonist, HC030031, at room temperature (RT) and subsequently exposed to low temperature (LT). Bladder specimens treated with HC030031 were evaluated for contractions through cumulative addition of the TRPA1 channel agonist trans-cinnamaldehyde. Two days before cystometric investigation, small interfering RNA (siRNA) targeting TRPA1 was transfected into urinary bladders. Then, cystometric investigations were performed on rats subjected to TRPA1 siRNA transfection at both RT and LT. Expression of TRPA1 channels in the urinary bladder was assessed through immunohistochemistry and real-time reverse transcription-polymerase chain reaction.

RESULTS

At RT, micturition patterns were unaffected by HC030031 treatment. However, upon exposure to LT, rats treated with HC030031 exhibited a reduction of LT-elicited bladder overactivity, as evidenced by inhibited decreases in voiding interval, micturition volume, and bladder capacity. Additionally, HC030031 inhibited trans-cinnamaldehyde-induced contractions. Immunohistochemical analysis showed the presence of TRPA1 channels in the urinary bladder. Notably, rats with TRPA1 siRNA-transfected bladders could partially inhibit bladder overactivity during LT exposure.

CONCLUSIONS

These findings indicate that pathways involving TRPA1 channels expressed in the urinary bladder could mediate the LT-elicited bladder overactivity.

Factors affecting urinary frequency after low-dose-rate brachytherapy for prostate cancer

OBJECTIVES

Lower urinary tract symptoms are transiently exacerbated by low-dose-rate brachytherapy (LDR-BT) for prostate cancer and recover to pretreatment levels 1 year thereafter. Generally, these symptoms are influenced by temperature. We aimed to search for factors affecting the lower urinary tract symptoms after seed implant including seasons.

METHODS

We retrospectively enrolled 812 patients who underwent LDR-BT at Nara Medical University Hospital from January 2010 to December 2018 and for whom the International Prostate Symptom Score, Overactive Bladder Symptom Score, and frequency volume charts were available. We investigated the relationships between lower urinary tract symptoms, 24-hours urinary frequency, 24-hours urinary volume before and after seed implant, radiation dose, and season of seed implant.

RESULTS

The mean age was 69.5 years. The mean prostate volume was 24.2 mL. The International Prostate Symptom Score, Overactive Bladder Symptom Score, and 24-hours urinary frequency increased until 3 months and gradually decreased over 6 months after seed implant. Multiple linear regression analysis revealed that 24-hours urinary frequency at 3 months after seed implant was significantly influenced by external beam radiotherapy, larger prostate volume before implant, higher 24-hours urinary frequency at baseline, larger 24-hours urinary volume at 3 months after implant, and performance of implant in summer.

CONCLUSIONS

Lower urinary tract symptoms worsened 3 months after seed implant of LDR-BT regardless of the season of implant. The urinary frequency 3 months after seed implant was slightly lower when seed implant was performed in the summer.

Seasonal changes in occurrence and severity of lower urinary tract symptoms-Tampere Aging Male Urologic Study (TAMUS)

OBJECTIVES

To determine if lower urinary tract symptoms (LUTS) involve seasonal variation and how this affects the severity of LUTS.

METHODS

A total of 3163 men aged 50 to 70 years were mailed a questionnaire on urinary symptoms. The overall response rate was 65.3% (2064 out of 3163 men). The men were asked whether their urinary symptoms showed variation in degree of difficulty according to time of year and if yes, when LUTS were the worst and the mildest. Ten different LUTS were evaluated with four response options for the severity of symptoms. Mean symptom scores and the proportions of symptomatic men were evaluated according to the presence of seasonal changes in different symptoms.

RESULTS

Overall, 17.1% of men reported seasonal variation in severity of LUTS, older men more frequently than younger men. Worse LUTS during winter were reported by 81% of the men reporting seasonal variation, and 93% reported that LUTS were relieved in summer. More seasonal variation was reported by men with comorbidities (stroke, neurological disease) and those with medical treatment for LUTS or operative treatment for benign prostatic hyperplasia. Men with more severe LUTS were more likely to report seasonal changes.

CONCLUSIONS

One out of six men reported seasonal changes in LUTS, with winter worsening and summer relieving the symptoms. Men with seasonal variation in LUTS had more severe LUTS in all 10 symptom groups that were investigated.

Impact of Cold Indoor Temperatures on Overactive Bladder: A Nationwide Epidemiological Study in Japan

OBJECTIVE

To assess the relationship between overactive bladder (OAB) and indoor temperatures in the living room and bedroom.

METHODS

Questionnaire data and indoor temperature measurements were obtained from a baseline survey collected during the winter months from November 2014 to March 2019. We performed multiple logistic regression to assess the relationships between OAB and indoor temperatures in the living room and bedroom.

RESULTS

The prevalence of overactive bladder was 16.4% among 4782 participants living in 2453 dwellings. The odds of having OAB were higher for participants whose average living room temperature at bedtime was lower than 12°C than for those whose average bedtime living room temperature was at least 18°C (adjusted odds ratio = 1.44, 95% confidence interval: 1.03-2.00). No association was observed between bedroom temperature and OAB.

CONCLUSION

These results suggest that thermal comfort in the living room-but not in the bedroom-may improve OAB symptoms. Additionally, using sufficient bedding may prevent cold bedrooms from having a negative impact in terms of OAB. Future studies should focus on housing interventions and education regarding lifestyle modification in patients with OAB.

Seasonal Variation of Overactive Bladder Symptoms in Female Patients

Purpose

To evaluate seasonal variations of overactive bladder (OAB) symptoms in women who visited hospital clinics.

Methods

Medical records of female patients treated for OAB symptoms from January 2011 to December 2017 were retrospectively reviewed. Patients with pyuria at the first visit, those who did not complete the questionnaire, and those with <3 overactive bladder symptom scores (OABSS) were excluded. Uroflowmetric parameters, 3-day micturition diary, and OABSS were analyzed.

Results

A total of 582 patients with OAB symptoms who visited the hospital were enrolled in this study. Patients were grouped into 1 of the 3 season groups (cold, intermediate, and hot) depending on the average temperature of the month that the patient first visited the urologic department outpatient clinic. The total OABSS was significantly different between the 3 season groups (cold [7.25±3.20] vs. intermediate [6.24±3.40] vs. hot [5.51±3.20], P=0.001). The proportion of patients who had moderate OAB symptoms (6≤OABSS) was higher in the cold season group (56.2%) than in the other season groups (intermediate, 42.1%; hot, 31.8%; P=0.002). Differences in the number of micturitions (12.12±4.56 vs. 10.95±4.39, P=0.021) and number of urgent urinary incontinence episodes (2.06±0.94 vs. 2.48±0.87, P=0.001) between the cold and hot season groups were also significant. However, differences in the nocturia episode, total daytime voided volume, and mean voided volume between season groups were not significant.

Conclusions

Different urinary symptoms and uroflowmetric parameters were correlated with seasonal variation. OAB symptoms might be worse in cold season than in other seasons.

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.

The oscillation of intracellular Ca2+ influx associated with the circadian expression of Piezo1 and TRPV4 in the bladder urothelium

We previously showed that bladder functions are controlled by clock genes with circadian rhythm. The sensation of bladder fullness (SBF) is sensed by mechano-sensor such as Piezo1 and TRPV4 in the mouse bladder urothelium. However, functional circadian rhythms of such mechano-sensors remain unknown. To investigate functional circadian changes of these mechano-sensors, we measured circadian changes in stretch-evoked intracellular Ca²⁺ influx ([Ca²⁺] _i ) using mouse primary cultured urothelial cells (MPCUCs). Using Ca²⁺ imaging, stretch-evoked [Ca²⁺] _i was quantified every 4 h in MPCUCs derived from wild-type (WT) and Clock ^Δ19/Δ19 mice, which showed a nocturia phenotype. Furthermore, a Piezo1 inhibitor GsMTx4 and a TRPV4 inhibitor Ruthenium Red were applied and stretch-evoked [Ca²⁺] _i in MPCUCs was measured to investigate their contribution to SBF. Stretch-evoked [Ca²⁺] _i showed a circadian rhythm in the WT mice. In contrast, Clock ^Δ19/Δ19 mice showed disrupted circadian rhythm. The administration of both GsMTx4 and Ruthenium Red eliminated the circadian rhythm of stretch-evoked [Ca²⁺] _i in WT mice. We conclude that SBF may have a circadian rhythm, which is created by functional circadian changes of Piezo1 and TRPV4 being controlled by clock genes to be active during wakefulness and inactive during sleep. Abnormalities of clock genes disrupt SBF, and induce nocturia.

Effect of pregnancy on cooling tone and rhythmic contractions of the rat urinary bladder

OBJECTIVES

Pregnancy is a physiological alteration that can affect urinary bladder. Cooling of urinary bladder smooth muscle is known as a potent stimulus to micturition due to an increase in muscle tone. The current study investigates the effects of pregnancy on cooling tone and on the rhythmic contractions of the urinary bladder.

METHODS

Twenty-four rats were used in this study as control group (non-pregnant) and pregnant group (18-20-day pregnancy). Isolated rat urinary muscle strips were suspended in organ baths containing Krebs' solution for isometric tension recording.

RESULTS

Cooling from 37 to 5 °C induced a rapid and reproducible increase in basal tone, proportional to cooling temperature. Cooling also increased the rhythmic activity (amplitude and frequency) at 30 and 25 °C, then decreased at 20 °C, and abolished at 15-5 °C. These responses were more pronounced in pregnant group than in control group. Rhythmic contractions were abolished in calcium-free, EGTA (1 mM)-containing Krebs' solution and in the presence of nifedipine, while they were not affected by CPA or TTX in both groups. Our investigation showed that the influx of extracellular calcium is important in inducing the rhythmic contractions.

CONCLUSIONS

Pregnancy increases cooling-induced contraction in pregnant rat urinary preparations and its rhythmic contractions including amplitude and frequency than non-pregnant rat. Rhythmic contractions are myogenic in nature and highly extracellular calcium dependent. They may play a crucial role in urinary bladder overactivity and incontinence during pregnancy.