Increased bladder wall thickness in diabetic and nondiabetic women with overactive bladder

Cold stress-induced bladder overactivity in type 2 diabetic mellitus rats is mitigated by the combination of a M3 -muscarinic antagonist and a β3 -adrenergic agonist

OBJECTIVES

Goto-Kakizaki (GK) rats with type 2 diabetes mellitus respond to low temperature (LT) environments with bladder overactivity, including increased voiding frequency and decreased voiding interval and micturition volume. We determined if bladder overactivity could be inhibited by treatment with the combination of a M₃ -muscarinic receptor antagonist and a β₃ -adrenergic receptor agonist.

METHODS

Ten-week-old female GK rats were fed a high-fat diet for 4 weeks. Cystometric investigations were conducted at room temperature (RT, 27 ± 2°C). The rats were then intraperitoneally administered the vehicle, the M₃ -muscarinic receptor antagonist solifenacin, the β₃ -adrenergic agonist mirabegron, or a combination of solifenacin and mirabegron. Ten minutes after the administrations, the rats were transferred to the LT environment (4 ± 2°C), where the cystometric measurements were continued. The expressions of both M₃ -muscarinic and β₃ -adrenergic receptors were investigated.

RESULTS

After transfer from RT to LT, both voiding interval and bladder capacity of the vehicle-, solifenacin-, or mirabegron-treated rats were significantly decreased. However, the combination of solifenacin and mirabegron significantly mitigated the bladder overactivity. While both M₃ -muscarinic and β₃ -adrenergic receptors were detected, the expression of M₃ -muscarinic receptor mRNA was significantly higher than that of β₃ -adrenergic receptor mRNA.

CONCLUSIONS

The cold stress-induced bladder overactivity was not improved by either the M₃ -muscarinic receptor antagonist or the β₃ -adrenergic receptor agonist alone. However, the combined treatment mitigated the cold stress responses. Combined therapy with M₃ -muscarinic antagonists and β₃ -adrenergic agonists could reduce side effects and improve the quality of life for diabetic patients with bladder overactivity.

Urinary bladder wall thickness in type 2 diabetes mellitus patients

Introduction

Diabetes mellitus is an increasing health challenge with accompanying urological complications. Over 50% of men and women with diabetes have bladder dysfunction. According to the current understanding of bladder dysfunction, it refers to a progressive condition encompassing a broad spectrum of lower urinary tract symptoms including urinary urgency, frequency, nocturia, and incontinence. Urinary bladder dysfunction has been classically described as diminished bladder sensation, poor contractility, and increased post-void residual urine, termed bladder cystopathy. Ultrasonography of the urinary bladder, which is a cheap, safe, radiation free, non-invasive and reliable imaging modality, may help to identify diabetes mellitus patients prone to develop urinary bladder dysfunction.

Method

The study population comprised 80 diabetic subjects recruited from the diabetic outpatient clinic and another 80 age- and sex-matched asymptomatic control subjects. Ultrasound scan of their urinary bladder wall was performed using a curvilinear transducer to determine the thickness and other sonographic features.

Results

Out of the 80 diabetic subjects, 30 (37.5%) were males, while 50 (62.5%) were females; of 80 non-diabetic control subjects, 40 (50%) were males and 40 (50%) were females. The mean age of the diabetic subjects was 59.5 ± 10.4 years with a range of 40–82 years, while that of the controls was 60.2 ± 7.4 years with a range of 40–85 years. There was no statistically significant difference (p = 0.637) between the mean age of the diabetic and control subjects. The mean urinary bladder wall thickness in the diabetics was greater than in the non-diabetics in the study subjects. There was a statistically significant difference between the urinary bladder thickness of diabetic subjects and the control group (p <0.001). The mean urinary bladder wall thickness of the male and female subjects included in this study was 2.84 ± 1.31 mm and 2.9 ± 1.37 mm, respectively, with no statistically significant difference between them (p = 0.159). It was statistically significant between diabetic men and women (p = 0.027). Using Spearman’s rank correlation to test the relationship between the glycaemic haemoglobin level of diabetic subjects and urinary bladder wall thickness, it was revealed that there was no correlation between these variables (Spearman’s rho = 0.119, p = 0.309). The relationship between the urinary bladder volume of diabetic subjects and their mean urinary bladder wall thickness showed no correlation either (Spearman’s rho = –0.009, p = 0.937). Only gender was a statistically significant predictor of urinary bladder wall thickness among other variables.

Conclusion

Mean bladder wall thickness in patients with type 2 diabetes mellitus was greater than in the control subjects, and also greater in diabetic men compared to diabetic women, but the difference did not attain statistical significance. Urinary bladder wall thickness of the diabetics did not correlate with their glycaemic haemoglobin levels. Only gender was found to be a predictor of bladder wall thickness.

Low-intensity extracorporeal shockwave therapy ameliorates diabetic underactive bladder in streptozotocin-induced diabetic rats

OBJECTIVES

To evaluate the therapeutic effect of once-weekly low-intensity extracorporeal shock wave therapy (Li-ESWT) on underactive bladder (UAB) in the streptozotocin (STZ)-induced diabetic rat model.

MATERIALS AND METHODS

In all, 36 female Sprague-Dawley rats were divided into three groups: normal control (NC), diabetes mellitus control (DMC), and DM with Li-ESWT (DM Li-ESWT). The two DM groups received an intraperitoneal 60 mg/kg STZ injection to induce DM. The Li-ESWT was applied toward the pelvis of the rats starting 4 weeks after STZ administration and lasting for 4 weeks. The Li-ESWT was given once weekly, with an energy flux density of 0.02 mJ/mm² at 3 Hz for 400 pulses. All rats underwent conscious cystometry, leak-point pressure (LPP) assessment, ex vivo organ-bath study, histology, immunofluorescence, and Western Blot analysis.

RESULTS

Conscious cystometry revealed voiding dysfunction in the DMC group, whereas the DM Li-ESWT group showed significantly improved voiding function, reflected in a reduced post-void residual urine volume and increased LPP compared to the DMC group. Ex vivo organ-bath studies showed that Li-ESWT enhanced muscle contractile activity of the bladder and urethra during electrical-field stimulation and drug stimulation. Histologically, Li-ESWT significantly restored bladder morphology, reflected by a reduction in the intravesical lumen area and increased muscle proportion of the bladder wall. Western Blot analysis showed higher smooth muscle actin expression in the bladder wall in the DM Li-ESWT group compared to the DMC group. Immunofluorescence showed decreased nerve-ending distribution, and destroyed and shortened nerve fibres in the DMC group, and recovery of neuronal integrity and innervation in the DM Li-ESWT group.

CONCLUSIONS

In conclusion, Li-ESWT ameliorated UAB and urinary incontinence in the diabetic UAB rat model. The improvement appears to be the result of restoration of bladder and urethral structure and function by Li-ESWT. Li-ESWT is non-invasive and may become a better alternative therapy for UAB. Further investigations are warranted.

Muscarinic receptors mediate cold stress-induced detrusor overactivity in type 2 diabetes mellitus rats

OBJECTIVES

This study determined if muscarinic receptors could mediate the cold stress-induced detrusor overactivity induced in type 2 diabetes mellitus rats.

METHODS

Ten-week-old female Goto-Kakizaki diabetic rats (n = 12) and Wister Kyoto non-diabetic rats (n = 12) were maintained on a high-fat diet for 4 weeks. Cystometric investigations of the unanesthetized rats were carried out at room temperature (27 ± 2°C) for 20 min. They were intravenously administered imidafenacin (0.3 mg/kg, n = 6) or vehicle (n = 6). After 5 min, the rats were transferred to a low temperature (4 ± 2°C) for 40 min where the cystometry was continued. The rats were then returned to room temperature for the final cystometric measurements. Afterwards, expressions of bladder muscarinic receptor M3 and M2 messenger ribonucleic acids and proteins were assessed by reverse transcription polymerase chain reaction and immunohistochemistry.

RESULTS

In non-diabetic Wister Kyoto rats, imidafenacin did not reduce cold stress-induced detrusor overactivity. In diabetic Goto-Kakizaki rats, just after transfer to a low temperature, the cold stress-induced detrusor overactivity in imidafenacin-treated rats was reduced compared with vehicle-treated rats. Within the urinary bladders, the ratio of M3 to M2 receptor messenger ribonucleic acid in the diabetic Goto-Kakizaki rats was significantly higher than that of the non-diabetic Wister Kyoto rats. The proportion of muscarinic M3 receptor-positive area within the detrusor in diabetic Goto-Kakizaki rats was also significantly higher than that in non-diabetic Wister Kyoto rats.

CONCLUSIONS

Imidafenacin partially inhibits cold stress-induced detrusor overactivity in diabetic Goto-Kakizaki rats. In this animal model, muscarinic M3 receptors partially mediate cold stress-induced detrusor overactivity.