Urodynamics and bladder muscarinic receptors in rats with cerebral infarction and bladder outlet obstruction

Effects of combined treatment with fesoterodine and mirabegron in a pelvic congestion rat model: Results from in vitro and in vivo functional studies

Objectives

To examine the effect of combining a nonselective muscarinic receptor antagonist, 5‐hydroxymethyl tolterodine (an active metabolite of fesoterodine), with a β3 adrenoceptor agonist, mirabegron, in a rat model of pelvic congestion.

Methods

The rat pelvic congestion model used female Sprague‐Dawley rats with their bilateral common iliac and uterine veins ligated. Expressions of M2 and M3 receptor subtypes in the urothelium and detrusor were detected by real‐time polymerase chain reaction assays. The effects of both drugs were investigated on isolated bladder strips contracted by electrical field stimulation. in vivo single cystometry was used to assess the effects of 5‐hydroxymethyl tolterodine and mirabegron independently or in combination on bladder capacity, micturition pressure, and threshold pressure.

Results

Pelvic congestion rats showed decreased bladder capacity compared with controls, but micturition pressure and threshold pressure were unchanged. Pelvic congestion model rats also demonstrated an approximately two‐fold increase in expression of both M2 and M3 receptor subtypes in the urothelium. Additive relaxant effects of 5‐hydroxymethyl tolterodine and mirabegron were observed in vitro in the electrical field stimulation‐induced contractions of bladder strips from pelvic congestion rats. In vivo, bladder capacity was increased significantly by a combination of 5‐hydroxymethyl tolterodine and mirabegron, with the combined effect exceeding the sum of the effects of monotherapies. Micturition pressure and threshold pressure did not significantly differ between groups.

Conclusions

The combination of 5‐hydroxymethyl tolterodine with mirabegron suggests the potential of synergistic effects in a rat pelvic congestion model.

[Neuroanatomical correlates between stroke lesions and urinary disorders: A narrative review]

CONTEXT

Stroke generates diverse urinary disorders, frequent but often under-diagnosed and thus untreated. Even though advances in the comprehension of the physiological voiding control and involved brain areas, the precise correspondence between lesion sites and observed urinary symptoms is not clearly established.

OBJECTIVE

This review aimed to update on this neuroanatomical correlates.

DOCUMENTARY SOURCES

The search focused on articles written in French or English, on PubMed, studying human beings or animals, published between the 1st of January 2000 and the 31st of August 2018 using the following keywords (stroke or hemiplegia) and (urinary incontinence or low urinary tract symptom or retention or overactive bladder or dysuria) and (anatomy or location or localization or area or lesion).

STUDIES SELECTION

The main author selected the most pertinent articles on abstracts and then on full text.

RESULTS

Twelve studies were included in our review. We could not fully confirm the neuroanatomical correlates based on the animal model. Frontoparietal lesions in urinary incontinence, role of the insula in the urinary retention, and systematic but different urinary symptoms in the brain stem lesions are the main findings.

LIMITS

Few studies were included, with varying methodologies and types of population.

CONCLUSION

A few cerebral areas damaged by stroke seem to be linked to certain urinary troubles, but new studies with a higher methodological quality are required to confirm this result.

The Aging Overactive Bladder: A Review of Aging-Related Changes from the Brain to the Bladder

PURPOSE OF REVIEW

To understand the current literature on age-related neural and detrusor changes associated with overactive bladder symptoms.

RECENT FINDINGS

Recent functional magnetic resonance imaging (fMRI) studies have unveiled an age-related decrease in the neural control of continence, represented in the insula, anterior cingulate cortex (ACC) and prefrontal cortex (PFC). Older individuals with overactive bladder symptoms also demonstrate heightened activation of the ACC with low volumes, representing increased bladder sensitivity or sense of urgency. At the level of the bladder, age-related changes in the urothelium, neurotransmitters/receptors (both muscarinic and purinergic), and inflammation [including nerve growth factor (NGF), monocyte chemoattractant protein-1 (MCP-1) and oxidative stress] are also associated with overactive bladder.

SUMMARY

Overactive bladder among older adults is a complex condition incorporating physiologic age-related changes from the brain to the bladder and beyond.

Bladder Transplantation of Amniotic Fluid Stem Cell may Ameliorate Bladder Dysfunction After Focal Cerebral Ischemia in Rat

The objective is to investigate whether human amniotic fluid stem cells (hAFSCs) grafting into the bladder may influence bladder functional and molecular changes in an animal stroke model. Female rats were divided into three groups: sham, middle cerebral artery occlusion (MCAO) alone, and MCAO plus 1 × 10⁶ hAFSCs transplanting into bladder wall. Bladder function was analyzed by cystometry at days 3 and 10 after MCAO. The expressions of bladder nerve growth factor (NGF), M2‐muscarinic, M3‐muscarinic, and P2X1 receptors were measured by immunohistochemistry and real‐time polymerase chain reaction. When compared with sham‐operated group, MCAO alone rats had significant increase in residual volume and decrease in voided volume and intercontraction interval; however, these bladder dysfunctions were improved following hAFSCs transplantation. The immunoreactivities of NGF, M3, and P2X1 significantly decreased at days 3 and 10, but M2 increased at day 3 after MCAO. Following hAFSCs transplantation, the immunoreactivities of NGF and P2X1 significantly increased at day 3, and M2 increased at day 10 after MCAO. The mRNAs of NGF, M2, and M3 significantly increased at day 3, but NGF and M2 decreased at day 10 after MCAO. Following hAFSCs transplantation, there was significant decrease in M2 mRNA at day 3 and increase in P2X1 mRNA at days 3 and 10 after MCAO. Bladder dysfunction caused by MCAO can be improved by hAFSCs transplanting into bladder which may be related to the expressions of bladder NGF, and muscarinic and P2X1 receptors. Stem Cells Translational Medicine2017;6:1227–1236

Nerve growth factor release from the urothelium increases via activation of bladder C-fiber in rats with cerebral infarction

AIMS

There are some reports that bladder C-fibers are partially involved in detrusor overactivity in patients with brain lesions. We investigated the contribution of bladder C-fiber to decreased bladder capacity in rats with cerebral infarction.

METHODS

Cerebral infarction was induced under halothane anesthesia by left middle cerebral artery occlusion with 4-0 nylon thread in female Sprague-Dawley rats. Intramural amounts of ATP and prostaglandin E₂ , in vivo and in vitro ATP, NGF, and prostaglandin E₂ release from the distended bladder urothelium, and changes in mRNA expressions of sensor molecules and receptors were monitored 6 h after the occlusion. Cystometry was performed in rats with or without resiniferatoxin pretreatment.

RESULTS

Overexpression of sensor molecule, transient receptor potential vanilloid-type channel 1, acid-sensing ion channel 2, purinergic receptors P2X₃ , and M₂ /M₃ muscarinic receptors was found in the bladder. These changes were accompanied by increases in ATP and NGF release from the urothelium. In contrast, when bladder C-fibers were desensitized by resiniferatoxin, no increase in NGF release from the urothelium was found either in vivo or in vitro. There was no difference in the percentage decrease in bladder capacity between cerebral infarction rats pretreated with resiniferatoxin and cerebral infarction rats without pretreatment.

CONCLUSIONS

Results indicate that expression of sensor molecules in the bladder is altered by distant infarction in the brain. ATP and NGF release from the urothelium also increased. NGF release was related to activation of bladder C-fibers. Bladder C-fibers might not contribute much to decreased bladder capacity caused by cerebral infarction.

Research Findings on Overactive Bladder

Several physiopathologic conditions lead to the manifestation of overactive bladder (OAB). These conditions include ageing, diabetes mellitus, bladder outlet obstruction, spinal cord injury, stroke and brain injury, Parkinson's disease, multiple sclerosis, interstitial cystitis, stress and depression. This review has discussed research findings in human and animal studies conducted on the above conditions. Several structural and functional changes under these conditions have not only been observed in the lower urinary tract, but also in the brain and spinal cord. Significant changes were observed in the following areas: neurotransmitters, prostaglandins, nerve growth factor, Rho-kinase, interstitial cells of Cajal, and ion and transient receptor potential channels. Interestingly, alterations in these areas showed great variation in each of the conditions of the OAB, suggesting that the pathophysiology of the OAB might be different in each condition of the disease. It is anticipated that this review will be helpful for further research on new and specific drug development against OAB.

Bladder angiotensin-II receptors: characterization and alteration in bladder outlet obstruction

BACKGROUND

It is assumed that angiotensin II (AngII) is significantly implicated in the pathogenesis of urinary dysfunction because of bladder outlet obstruction (BOO).

OBJECTIVE

The current study was undertaken to characterize AngII receptors in the rat bladder in relation to BOO.

MEASUREMENTS

Bladder AngII receptors were measured by a sensitive binding assay using a specific antagonist radioligand, [(125)I]-Sar(1)-Ile(8)-AngII, in bladder outlet-obstructed rats with and without repeated oral administration of telmisartan.

RESULTS AND LIMITATIONS

[(125)I]-Sar(1)-Ile(8)-AngII bound specifically to the rat bladder homogenates with high affinity. This specific binding of [(125)I]-Sar(1)-Ile(8)-AngII was concentration-dependently displaced by the type 1 subtype (AT(1))-selective antagonists. These findings revealed the significant existence of pharmacologically relevant AngII (AT(1)) receptors in the bladder with relatively high density. Oral administration of telmisartan in rats has been shown to bind to the bladder AngII receptors. Bladder weight was about three times greater in bladder outlet-obstructed rats than in sham rats. Maximal number of binding sites (B(max)) for [(125)I]-Sar(1)-Ile(8)-AngII binding in the bladder was significantly (48%) decreased in the bladder-outlet rats when compared with sham rats, suggesting the down regulation of pharmacologically relevant AngII receptor sites. Notably, repeated oral administration of telmisartan (3mg/kg/d, 14 d) in rats completely prevented the development of a BOO-induced decrease in B(max) for bladder [(125)I]-Sar(1)-Ile(8)-AngII binding. Telmisartan treatment also effectively attenuated the increase in the bladder-wet weight caused by urinary outlet obstruction.

CONCLUSIONS

Bladder AngII may be at least partly associated with the pathogenesis of urinary dysfunction occurring subsequent to BOO through stimulation of the AT(1) receptor subtype.