A promising protein responsible for overactive bladder in ovariectomized mice

Review of Animal Models to Study Urinary Bladder Function

Simple Summary

The treatment of urinary bladder dysfunction requires the knowledge of bladder function, which involves physiology, pathology, and even psychology. Several animal models are available to study a variety of bladder disorders. These models include animals from rodents, such as mice and rats, to nonhuman primates, such as rabbits, felines, canines, pigs, and mini pigs. This review adapted animal models to study bladder function according to facility, priority, and disease.

Abstract

The urinary bladder (UB) serves as a storage and elimination organ for urine. UB dysfunction can cause multiple symptoms of failure to store urine or empty the bladder, e.g., incontinence, frequent urination, and urinary retention. Treatment of these symptoms requires knowledge on bladder function, which involves physiology, pathology, and even psychology. There is no ideal animal model for the study of UB function to understand and treat associated disorders, as the complexity in humans differs from that of other species. However, several animal models are available to study a variety of other bladder disorders. Such models include animals from rodents to nonhuman primates, such as mice, rats, rabbits, felines, canines, pigs, and mini pigs. For incontinence, vaginal distention might mimic birth trauma and can be measured based on leak point pressure. Using peripheral and central models, inflammation, bladder outlet obstruction, and genetic models facilitated the study of overactive bladder. However, the larger the animal model, the more difficult the study is, due to the associated animal ethics issues, laboratory facility, and budget. This review aims at facilitating adapted animal models to study bladder function according to facility, priority, and disease.

Astragalus polysaccharides and astragaloside IV ameliorates cyclophosphamide-induced mouse model of overactive bladder

OBJECTIVE

Previous studies have shown that Astragalus polysaccharides (APS) and Astragaloside IV (AS-IV) protect against inflammation-related cell damage and exhibit immune enhancement. Since urothelial injury may result in an overactive bladder (OAB), the aim of this study was to investigate the efficacy of APS and AS-IV on urothelial injury in an experimental animal model.

MATERIALS AND METHODS

The effects of APS and AS-IV on the proliferation and migration of primary human urothelial cells (HUCs) or primary human fibroblast cells (HFCs) were assessed using an in vitro wounding model and colorimetric thiazolyl blue assays. Sixty virgin female mice were randomized into five groups: group 1-saline-injected plus treatment with H₂O, group 2-cyclophosphamide (CYP) plus treatment with H₂O, group 3-CYP plus treatment with solifenacin succinate (SS; 10 mg/kg), group 4-CYP plus treatment with AS-IV (100 mg/kg), and group 5-CYP plus treatment with APS (100 mg/kg). Cystometry assessment was conducted and cell junction-associated protein zonula occludens-2 (ZO-2) expression was measured. Voiding interval values (time between voids) were assessed in mice under anesthesia. Lastly, immunohistochemistry analysis was used to confirm the location and level, respectively, of ZO-2 expression.

RESULTS

APS and AS-IV did not influence the cell viability but increased migration in HFCs compared with the controls. The OAB mice showed significantly lower voiding interval values. Voiding interval values were significantly higher in the CYP plus treatment with APS (100 mg/kg) and AS-IV (100 mg/kg) groups than in the CYP-induced OAB group. Additionally, the expression of ZO-2, a tight junction protein, was increased in the CYP plus treatment APS (100 mg/kg) and AS-IV (100 mg/kg) groups compared with the CYP-induced OAB group.

CONCLUSION

These findings suggest that APS and AS-IV modulate urothelial wound healing, which ameliorates urinary frequency of mice treated with CYP. APS or AS-IV may have the potential benefit of acting as urothelial wound healing modulators.

Vaginal estrogen therapy is associated with increased Lactobacillus in the urine of postmenopausal women with overactive bladder symptoms

BACKGROUND

Previous work has shown that the vaginal microbiome decreases in Lactobacillus predominance and becomes more diverse after menopause. It has also been shown that estrogen therapy restores Lactobacillus dominance in the vagina and that topical estrogen is associated with overactive bladder symptom improvement. We now know that the bladder contains a unique microbiome and that increased bladder microbiome diversity is associated with overactive bladder. However, there is no understanding of how quickly each pelvic floor microbiome responds to estrogen or if those changes are associated with symptom improvement.

OBJECTIVE

This study aimed to determine if estrogen treatment of postmenopausal women with overactive bladder decreases urobiome diversity.

STUDY DESIGN

We analyzed data from postmenopausal participants in 2 trials (NCT02524769 and NCT02835846) who chose vaginal estrogen as the primary overactive bladder treatment and used 0.5 g of conjugated estrogen (Premarin cream; Pfizer, New York City, NY) twice weekly for 12 weeks. Baseline and 12-week follow-up data included the Overactive Bladder questionnaire, and participants provided urine samples via catheter, vaginal swabs, perineal swabs, and voided urine samples. Microbes were detected by an enhanced culture protocol. Linear mixed models were used to estimate microbiome changes over time. Urinary antimicrobial peptide activity was assessed by a bacterial growth inhibition assay and correlated with relative abundance of members of the urobiome.

RESULTS

In this study, 12 weeks of estrogen treatment resulted in decreased microbial diversity within the vagina (Shannon, P=.047; Richness, P=.043) but not in the other niches. A significant increase in Lactobacillus was detected in the bladder (P=.037) but not in the vagina (P=.33), perineum (P=.56), or voided urine (P=.28). The change in Lactobacillus levels in the bladder was associated with modest changes in urgency incontinence symptoms (P=.02). The relative abundance of the genus Corynebacterium correlated positively with urinary antimicrobial peptide activity after estrogen treatment.

CONCLUSION

Estrogen therapy may change the microbiome of different pelvic floor niches. The vagina begins to decrease in diversity, and the bladder experiences a significant increase in Lactobacillus levels; the latter is correlated with a modest improvement in the symptom severity subscale of the Overactive Bladder questionnaire.

Managing overactive bladder

Overactive bladder (OAB) is a common and distressing condition which is known to increase with age and has a significant effect on quality of life. Whilst OAB is a symptomatic diagnosis, many patients will require basic investigations prior to initiating the appropriate management. This article will review the initial clinical assessment and management of women complaining of OAB including conservative measures and drug therapy, and will also focus on the role of estrogen. In addition, the management of refractory OAB will also be discussed including more invasive strategies such as neuromodulation, Botulinum Toxin, and reconstructive surgery.