Preventive Effects of Long-Term Caloric Restriction on Aging Related In Vivo Bladder Dysfunction and Molecular Biological Changes in the Bladder and Dorsal Root Ganglia in Rats

Spinal CRH facilitates the micturition reflex via the CRH2 receptor in rats with normal bladder and bladder outlet obstruction

Lower urinary tract symptoms (LUTS) significantly affect patient quality of life. Treatment options for bladder outlet obstruction (BOO) due to benign prostatic hyperplasia (BPH) (a common cause of LUTS) are insufficient to relieve discomfort. As the incidence of BPH is increasing, new pharmacological targets for LUTS treatment are required. Corticotropin-releasing hormone (CRH) is a neuropeptide that controls normal micturition in rodents. Herein, we investigated the role of spinal CRH in regulating micturition in sham and BOO rats, and evaluated CRH as a therapeutic target for bladder dysfunction in BOO model Sprague-Dawley rats. Histological analysis, cystometry with intrathecal administration of CRH agonists/antagonists, western blotting, and real-time PCR assessed the role of CRH and its receptors (CRHR1 and CRHR2) in micturition in sham and BOO rats. CRH administration shortened the voiding interval, while pretreatment with antagonists against CRHR2 (but not CRHR1) suppressed CRH-induced frequent voiding. Western blotting confirmed CRHR1 expression in the dorsal root ganglia (DRG) and bladder, but not the spinal cord, of rats. Real-time PCR showed higher CRHR2 mRNA expression in the spinal cord and DRG than in the bladder in both groups. Overall, spinal CRH facilitates the micturition reflex via CRHR2, and is a promising therapeutic target for LUTS.

Impaired nitric oxide mechanisms underlying lower urinary tract dysfunction in aging rats

The study aimed to investigate the bladder and urethral activity and nitric oxide (NO)-related molecular changes in aging rats. Rats were divided into two groups: Group Y (young rats; 12 wk) and Group A (aging rats; 15 mo). A 24-h voiding assay was performed, and the urodynamic parameters were evaluated using awake cystometry (CMG) and urethral perfusion pressure (UPP) recordings under urethane anesthesia. The mRNA expression levels of NO-, ischemia-, and inflammation-related markers in urethra and bladder tissues and cGMP levels in the urethra were assessed. Body weight was significantly higher in Group A than in Group Y. Voiding assay results (24 h) were insignificant. In the CMG, the number of non-voiding contractions per voiding cycle and post-void residual volume were significantly higher in Group A than in Group Y; voiding efficiency was significantly lower in Group A than in Group Y. In the UPP recordings, the urethral pressure reduction and high-frequency oscillation (HFO) amplitude were significantly lower in Group A than in Group Y. The mRNA expression levels of Hif-1α, Vegf-a, and Tgf-β1 in the bladder were significantly higher in Group A than in Group Y. The mRNA expression levels of Nos1 and Prkg1 and the cGMP concentrations in the urethra were significantly lower in Group A than in Group Y. Aging rats can be useful models for studying the natural progression of age-related lower urinary tract dysfunctions, for which impaired NO-mediated transmitter function is likely to be an important mechanism.NEW & NOTEWORTHY Aging rats can be useful models for studying the natural progression of age-related lower urinary tract dysfunctions, for which impaired nitric oxide-mediated transmitter function is likely to be an important mechanism.

Sarcopenia and Visceral Obesity are Significantly Related to Severe Storage Symptoms in Geriatric Female Patients

Purpose

This study aimed to elucidate the relationship of psoas muscle atrophy and visceral obesity with lower urinary tract symptoms in geriatric female patients.

Patients and Methods

We retrospectively reviewed the medical records of female patients aged ≥65 years. The psoas muscle index was defined, using computed tomography, as the cross-sectional area of the psoas muscle at the third lumbar vertebral level divided by the body surface area. We also measured visceral fat area at the umbilical level using computed tomography. We used logistic regression analysis to examine the relationships between the International Prostate Symptom Score (total score, voiding subscore, and storage subscore) and variables, such as age, body mass index, psoas muscle index, and visceral fat area. The International Prostate Symptom Score was categorized as mild, moderate, or severe.

Results

One hundred thirty-nine patients were included in our study. In the logistic regression analysis, we found statistically significant relationships between severe (versus mild-to-moderate) International Prostate Symptom Score storage subscore and variables, including low and high levels of psoas muscle index and visceral fat area, respectively. We could not find any significant relationships between the International Prostate Symptom Score total score and voiding subscore and the variables.

Conclusion

Psoas muscle atrophy and visceral fat accumulation are potential risk factors for severe storage symptoms in female patients aged ≥65 years.

Average urinary flow rate and its association with handgrip strength

BACKGROUND

Voiding dysfunction became a difficult problem for the elderly because of the underactive bladder (UAB). It was considered that the degeneration of detrusor muscle was the main etiology. In recent years, more articles focus on relationship between UAB and decreased muscle strength. Besides, handgrip strength (HGS) is an early indicator to detect frailty and muscle weakness in systemic reviews.

METHOD

Our study involved 2258 males from NHANES datasets (2011-2012, who were divided into quartiles by urine flow rate (UFR), which was measured by uroflowmetry. Multivariate regression models were performed to analyze the associations between UFR and HGS.

RESULTS

The UFR had a positive correlation to the HGS by multivariate regression models in males (β coefficient: 1.348, 95% confidence interval (CI): 0.530, 2.166, p = 0.001). The male participants with the highest quartile of UFR have a greater HGS than those with lowest quartile of UFR (β coefficient: 4.546, 95% CI: 2.462, 6.630, p < 0.001). Higher UFR was associated with lower odds of low HGS (OR: 0.489, 95% CI: 0.350, 0.684, p < 0.001) in the fully-adjusted model.

CONCLUSIONS

Our research highlighted that the UFR had a strong associated with the HGS in the healthy group.

Lacking transient receptor potential melastatin 2 attenuates lipopolysaccharide-induced bladder inflammation and its associated hypersensitivity in mice

OBJECTIVE

To study the role of transient receptor potential melastatin 2 in bladder function and inflammation-associated hypersensitivity.

METHODS

We evaluated physiological function of the bladder and intravesical lipopolysaccharide-induced inflammatory nociceptive responses in female wild-type and transient receptor potential melastatin 2-knockout mice. In vivo frequency/volume and decerebrated unanesthetized cystometry measurements, as well as in vitro detrusor strip functional studies, were carried out to evaluate bladder function. Mice received intravesical lipopolysaccharide (2.0 mg/mL) or saline instillation to evaluate responses to bladder inflammation. Voiding and bladder pain-like behaviors, cystometry measurements and histological evaluation were carried out before and after intravesical lipopolysaccharide instillation.

RESULTS

Few phenotypic differences in in vivo and in vitro physiological function were found between the two genotypes. Comparison of measurements taken before and 24-48 h after intravesical lipopolysaccharide instillation showed that voiding parameters did not change in transient receptor potential melastatin 2-knockout mice, whereas an increased voiding frequency was observed in wild-type mice. At 24 h after intravesical lipopolysaccharide instillation, the numbers of bladder pain-like behaviors and of infiltrated inflammatory cells in the bladder submucosal layer were significantly increased, and the voided volume and the intercontraction interval were significantly decreased on cystometry measurements in wild-type mice compared with those in both transient receptor potential melastatin 2-knockout mice and in wild-type mice treated with saline instillation.

CONCLUSIONS

Although the physiological roles of transient receptor potential melastatin 2 channels in the bladder might be limited, inflammation and associated hypersensitivity of the bladder caused by intravesical lipopolysaccharide instillation are attenuated in transient receptor potential melastatin 2-knockout mice, suggesting pathophysiological roles of transient receptor potential melastatin 2 channels in these processes.

Calorie restriction protects against apoptosis, mitochondrial oxidative stress and increased calcium signaling through inhibition of TRPV1 channel in the hippocampus and dorsal root ganglion of rats

The TRPV1 channel is activated in neurons by capsaicin, oxidative stress, acidic pH and heat factors, and these factors are attenuated by the antioxidant role of calorie restriction (CR). Hence, we investigated the hypothesis that the antioxidant roles of CR and food frequency (FF) may modulate TRPV1 activity and apoptosis through inhibition of mitochondrial oxidative stress in hippocampal (HIPPON) and dorsal root ganglion neurons (DRGN). We investigated the contribution of FF and CR to neuronal injury and apoptosis through inhibition of TRPV1 in rats. We assigned rats to control, FF and FF + CR groups. A fixed amount of food ad libitum was supplemented to the control and FF groups for 20 weeks, respectively. FF + CR group were fed the same amount of food as the control group but with 20% less calories during the same period. In major results, TRPV1 currents, intracellular Ca²⁺ levels, apoptosis, reactive oxygen species, mitochondrial depolarization, PARP-1 expression, caspase 3 and 9 activity and expression values were found to be increased in the HIPPON and DRGN following FF treatment, and these effects were decreased following FF + CR treatment. The FF-induced decrease in cell viability of HIPPO and DRGN, and vitamin E concentration of brain, glutathione peroxidase, vitamin A, and β-carotene values of the HIPPO, DRGN, plasma, liver and kidney were increased by FF + DR treatment, although lipid peroxidation levels in the same samples were decreased. In conclusion, CR reduces FF-induced increase of oxidative stress, apoptosis and Ca²⁺ entry through TRPV1 in the HIPPON and DRGN. Our findings may be relevant to the etiology and treatment of obesity following CR treatment.

The aging bladder insights from animal models

Alterations in bladder function with aging are very common and are very likely to represent an increasing healthcare problem in the years to come with the general aging of the population. In this review the authors describe the prevalence of lower urinary tract symptoms (LUTS) and comment upon potential mechanisms which may be responsible for the increasing prevalence of lower LUTS with increasing age, based on laboratory studies. It is clear that there is a complex interplay between the various components of the neural innervation structure of the bladder in leading to changes with age, which are likely to underpin the LUTS which are seen in the aging bladder.

Intravesical Activation of the Cation Channel TRPV4 Improves Bladder Function in a Rat Model for Detrusor Underactivity

BACKGROUND

Improvement of bladder emptying by modulating afferent nerve activity is an attractive therapeutic strategy for detrusor underactivity. Transient receptor potential vanilloid 4 (TRPV4) is a sensory ion channel in urothelial cells that contribute to the detection of bladder filling.

OBJECTIVE

To investigate the potential benefit of intravesical TRPV4 agonists in a pelvic nerve injury rat model for detrusor underactivity.

DESIGN, SETTING, AND PARTICIPANTS

Female wild-type and Trpv4 knockout rats underwent sham surgery or bilateral pelvic nerve injury (bPNI). Four weeks later, rats underwent cystometry with infusion of the TRPV4 agonist GSK1016790A. Bladders were harvested for in vitro pharmacological studies, quantitative reverse polymerase chain reaction and immunohistochemistry.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Data are expressed as median ± interquartile range. Statistical comparisons were made using the Mann-Witney U test and Wilcoxon signed rank test as appropriate.

RESULTS AND LIMITATIONS

Rats with bPNI showed a phenotype characteristic of detrusor underactivity with lower-amplitude voiding contractions, decreased voiding frequency, and increased postvoid residual. Intravesical application of GSK1016790A increased voiding frequency and reduced postvoid residual in wild-type, but not Trpv4^-/-, rats. In isolated bladder strips, GSK1016790A did not induce relevant contractions, indicating that the observed improvements in bladder function are the result of increased afferent signalling through TRPV4 activation, rather than a local effect on the detrusor. The altered urinary phenotype of Trpv4^-/- mice was not apparent in the Trpv4^-/- rat model, suggesting species-related functional variations. Our results are limited to the preclinical setting in rodents.

CONCLUSIONS

Intravesical activation of TRPV4 improves bladder dysfunction after bPNI by increasing afferent signalling.

PATIENT SUMMARY

We demonstrate that the sensory protein transient receptor potential vanilloid 4 (TRPV4) can be targeted to improve bladder function in animals that have iatrogenic injury to the nerves innervating the bladder. Further research is required to determine whether these results can be translated to patients with an underactive bladder.

Age-related changes in function and gene expression of the male and female mouse bladder

We investigated age-related changes in in vivo and in vitro functions and gene expression of the bladder of male and female mice. Mature and aged (12 and 27–30 month old) C57BL/6 mice of both sexes were used. Frequency volume, conscious free-moving cystometry and detrusor contractile and relaxant properties in in vitro organ bath were evaluated. mRNA expression level of muscarinic, purinergic, and β-adrenergic receptors and gene expression changes by cDNA microarray analysis of the bladder were determined. Cystometry demonstrated storage and voiding dysfunctions with ageing in both sexes. Detrusor strips from aged mice showed weaker contractile responses particularly in the cholinergic component and weaker relaxant responses to isoproterenol. These age-related impairments were generally severer in males. mRNA expression of bladder tissue was decreased for M3 muscarinic receptors in aged males and β2-adrenoceptors in aged females. cDNA microarray analysis results, albeit substantial sex difference, indicated “cell-to-cell signaling and interaction” as the most common feature of age-related gene expression. In summary, aged mice demonstrated voiding and storage dysfunctions resembling to detrusor hyperactivity with impaired contractility (DHIC), which were more pronounced in males. Genomic changes associated with aging may contribute to the age-related bladder functional deterioration in mice.

Pathophysiology of the underactive bladder

Underactive bladder (UAB), which has been described as a symptom complex suggestive of detrusor underactivity, is usually characterized by prolonged urination time with or without a sensation of incomplete bladder emptying, usually with hesitancy, reduced sensation on filling, and slow stream often with storage symptoms. Several causes such as aging, bladder outlet obstruction, diabetes mellitus, neurologic disorders, and nervous injury to the spinal cord, cauda equine, and peripheral pelvic nerve have been assumed to be responsible for the development of UAB. Several contributing factors have been suggested in the pathophysiology of UAB, including myogenic failure, efferent and/or afferent dysfunctions, and central nervous system dysfunction. In this review article, we have described relationships between individual contributing factors and the pathophysiology of UAB based on previous reports. However, many pathophysiological uncertainties still remain, which require more investigations using appropriate animal models.