Age-associated bladder and urethral coordination impairment and changes in urethral oxidative stress in rats

Effects of low-intensity extracorporeal shock wave therapy on lipopolysaccharide cystitis in a rat model of interstitial cystitis/bladder pain syndrome

PURPOSE

To investigate the effect of low-intensity extracorporeal shock wave therapy (LiESWT) on lipopolysaccharide (LPS)-induced cystitis in an animal model of interstitial cystitis/bladder pain syndrome (IC/BPS).

METHODS

Sprague-Dawley rats were divided into three groups: control, cystitis (LPS group, intravesical injection of LPS (1 mg) twice), and cystitis with LiESWT (LiESWT group). On the third and fourth days, LiESWT was administered (0.12 mJ/mm2, 300 shots each time) on the lower abdomen toward the bladder. On the seventh day, the rats underwent pain assessment and a metabolic cage study. Subsequently, a continuous cystometrogram (CMG) was performed under urethane anaesthesia. Immunohistochemical studies were also performed, including S-100 staining, an immunohistochemical marker of Schwann cells in the bladder.

RESULTS

In the LPS group, the pain threshold in the lower abdomen was significantly lower than that in the control group. In the metabolic cage study, the mean voided volume in the LPS group significantly increased. The CMG also revealed a significant decrease in bladder contraction amplitude, compatible with detrusor underactivity in the LPS group. Immunohistochemical studies showed inflammatory changes in the submucosa, increased fibrosis, and decreased S-100 stain-positive areas in the muscle layer of the LPS group. In the LiESWT group, tactile allodynia and bladder function were ameliorated, and S-100 stain-positive areas were increased.

CONCLUSION

By restoring nerve damage, LiESWT improved lower abdominal pain sensitivity and bladder function in an LPS-induced cystitis rat model. This study suggests that LiESWT may be a new therapeutic modality for IC/BPS.

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.

Effects of losartan on bladder dysfunction due to aging-related severe hypertension in rats

Aging is a major risk factor for bladder dysfunction. Anti-hypertensive drugs, angiotensin II type 1 receptor blockers (ARBs), are reported to ameliorate lower urinary tract dysfunction in rodent models and humans. We aimed to examine the preventive effect of an ARB, losartan, against bladder dysfunction due to aging-related severe hypertension. Male spontaneously hypertensive rats (SHRs) (36-week-old) were administered losartan (0, 3, or 10 mg/kg, p.o.) for 18 weeks. Age-matched, vehicle-treated Wistar Kyoto rats (WKYs) were used as controls. After the treatments, bladder and renal weight, mean blood pressure, and voiding parameters were measured. Additionally, detrusor thickness and bladder arterial wall thickness were evaluated using hematoxylin and eosin staining. Renal morphology was also assessed using periodic acid-Schiff staining. Compared to WKYs, SHRs demonstrated significantly higher bladder weight/body weight ratio (BBR), renal weight/body weight ratio, mean blood pressure, detrusor thickness, bladder arterial wall thickness, urine output, water intake, post-voiding residual urine volume, bladder capacity, intercontraction interval, and rate of glomerular and tubular injury and a lower urine osmolality. A low dose of losartan decreased the urine output, post-voiding residual urine volume, and bladder capacity in SHRs but not mean blood pressure in SHRs. A high dose of losartan decreased the BBR, mean blood pressure, detrusor thickness, bladder arterial wall thickness, post-voiding residual urine volume, bladder capacity, intercontraction interval, and glomerular and tubular injury in SHRs. Losartan inhibits bladder dysfunction in aged SHRs. The ARB losartan might be a preventive drug for bladder dysfunction due to aging-related severe hypertension.