Intracellular signaling pathways of muscarinic acetylcholine receptor-mediated detrusor muscle contractions.

Acetylcholine plays an essential role in the regulation of detrusor muscle contractions, and antimuscarinics are widely used in the management of overactive bladder syndrome. However, several adverse effects limit their application and patients' compliance. Thus, this study aimed to further analyze the signal transduction of M2 and M3 receptors in the murine urinary bladder to eventually find more specific therapeutic targets. Experiments were performed on adult male wild-type, M2, M3, M2/M3, or Gαq/11 knockout (KO), and pertussis toxin (PTX)-treated mice. Contraction force and RhoA activity were measured in the urinary bladder smooth muscle (UBSM). Our results indicate that carbamoylcholine (CCh)-induced contractions were associated with increased activity of RhoA and were reduced in the presence of the Rho-associated kinase (ROCK) inhibitor Y-27632 in UBSM. CCh-evoked contractile responses and RhoA activation were markedly reduced in detrusor strips lacking either M2 or M3 receptors and abolished in M2/M3 KO mice. Inhibition of Gαi-coupled signaling by PTX treatment shifted the concentration-response curve of CCh to the right and diminished RhoA activation. CCh-induced contractile responses were markedly decreased in Gαq/11 KO mice; however, RhoA activation was unaffected. In conclusion, cholinergic detrusor contraction and RhoA activation are mediated by both M2 and M3 receptors. Furthermore, whereas both Gαi and Gαq/11 proteins mediate UBSM contraction, the activation at the RhoA-ROCK pathway appears to be linked specifically to Gαi. These findings may aid the identification of more specific therapeutic targets for bladder dysfunctions.NEW & NOTEWORTHY Muscarinic acetylcholine receptors are of utmost importance in physiological regulation of micturition and also in the development of voiding disorders. We demonstrate that the RhoA-Rho-associated kinase (ROCK) pathway plays a crucial role in contractions induced by cholinergic stimulation in detrusor muscle. Activation of RhoA is mediated by both M2 and M3 receptors as well as by Gi but not Gq/11 proteins. The Gi-RhoA-ROCK pathway may provide a novel therapeutic target for overactive voiding disorders.

[The treatment of overactive bladder syndrome with onabotulinumtoxinA therapy]. / Hiperaktív (túlmuködo) húgyhólyag kezelése botulinumtoxin-A-terápiával.

Introduction: Overactive bladder syndrome is an endemic phenomenon, which has a significant impact on the quality of life. In cases where conservative treatment fails, intradetrusor onabotulinumtoxinA injection can be used as second-line therapy. Objective: To assess the safety and efficacy of onabotulinumtoxinA treatment in the management of non-neurogenic detrusor overactivity among our patients. Also, to examine the influence of perioperative factors on the effects of the efficacy. Method: We have retrospectively collected the perioperative data of 33 patients treated with intradetrusor BOTOX®. The assessment of the efficacy and complications was done by the examination of patient files and questionnaires. The results obtained during the statistical analysis were considered significant for p<0.05. Results: We have not experienced notable complications after the procedures. Only 6 patients had residual urine (p = 0.024), none of them needed to be catheterized. We have observed significant decrease in the incidence of frequency, nocturia, urgency and incontinence, just as in the number of pads needed daily (p<0.01). Quality of life and general health were significantly improved (p<0.001). We have not found any significant connection between preoperative factors and efficacy (72.7%). Discussion: Our results considering the relief of symptoms are well in line with international data. The fact that our rate of complications is - in international comparison - outstanding can be explained by a more careful patient selection and thorough preoperative assessment. Conclusion: OnabotulinumtoxinA therapy is a safe and effective solution of therapy-refractory overactive bladder. We could not identify any perioperative factor to predict postoperative efficacy of therapy. Orv Hetil. 2021; 162(36): 1459-1465.

Narrow Vagina as a Predictor of Obstructive Voiding Dysfunction after Transobturator Sling Surgery.

BACKGROUND: Voiding dysfunction (VD) is a potential complication after female midurethral sling operations. OBJECTIVES: Our goal was to assess the rate of obstructive VD after -transobturator tension-free tape (TOT) procedures and to find perioperative risk factors (RFs) predicting postoperative voiding problems. METHODS: We have retrospectively evaluated the perioperative data of 397 women who underwent TOT operations. Significant post-void residual (PVR) (>50 mL) was considered as the primary (objective) end point of the study, the voiding difficulty as the secondary (subjective) 1. First univariate analysis and then multivariate logistic regression were performed, with a 5% significance level. RESULTS: Significant PVR was present in 51 (12.8%) women; catheterization was needed in 21 (5.3%) and reoperation in 3 (0.8%) cases. Seventy women (17.6%) experienced postoperative voiding difficulty. Narrow vagina (<2 cm), older age >70 years, and preoperative voiding difficulty were independent RFs for significant PVR (odds ratio: 5.07, 2.14, 5.38, respectively, p < 0.05). Preoperative overactive bladder syndrome and previous pelvic organ prolapse surgery were considered independent RFs for postoperative voiding difficulty. CONCLUSIONS: Older age, narrow vagina, or preoperative voiding difficulty increases the chance for significant postoperative PVR. These patients should be chosen and counseled appropriately.

Isoprostanes evoke contraction of the murine and human detrusor muscle via activation of the thromboxane prostanoid TP receptor and Rho kinase.

Local or systemic inflammation can severely impair urinary bladder functions and contribute to the development of voiding disorders in millions of people worldwide. Isoprostanes are inflammatory lipid mediators that are upregulated in the blood and urine by oxidative stress and may potentially induce detrusor overactivity. The aim of the present study was to investigate the effects and signal transduction of isoprostanes in human and murine urinary bladders in order to provide potential pharmacological targets in detrusor overactivity. Contraction force was measured with a myograph in murine and human urinary bladder smooth muscle (UBSM) ex vivo. Isoprostane 8-iso-PGE2 and 8-iso-PGF2α evoked dose-dependent contraction in the murine UBSM, which was abolished in mice deficient in the thromboxane prostanoid (TP) receptor. The responses remained unaltered after removal of the mucosa or incubation with tetrodotoxin. Smooth muscle-specific deletion of Gα12/13 protein or inhibition of Rho kinase by Y-27632 decreased the contractions. In Gαq/11-knockout mice, responses were reduced and in the presence of Y-27632 abolished completely. In human UBSM, the TP agonist U-46619 evoked dose-dependent contractions. Neither atropine nor the purinergic receptor antagonist pyridoxalphosphate-6-azophenyl-2',4'-disulfonic acid decreased the effect, indicating that TP receptors directly mediate detrusor muscle contraction. 8-iso-PGE2 and 8-iso-PGF2α evoked dose-dependent contraction in the human UBSM, and these responses were abolished by the TP antagonist SQ-29548 and were decreased by Y-27632. Our results indicate that isoprostanes evoke contraction in murine and human urinary bladders, an effect mediated by the TP receptor. The G12/13-Rho-Rho kinase pathway plays a significant role in mediating the contraction and therefore may be a potential therapeutic target in detrusor overactivity.NEW & NOTEWORTHY Voiding disorders affect millions of people worldwide. Inflammation can impair urinary bladder functions and contribute to the development of detrusor overactivity. The effects and signal transduction of inflammatory lipid mediator isoprostanes were studied in human and murine urinary bladders ex vivo. We found that isoprostanes evoke contraction, an effect mediated by thromboxane prostanoid receptors. The G12/13-Rho-Rho kinase signaling pathway plays a significant role in mediating the contraction and therefore may be a potential therapeutic target.

Signaling Pathways Mediating Bradykinin-Induced Contraction in Murine and Human Detrusor Muscle.

Bradykinin (BK) has been proposed to modulate urinary bladder functions and implicated in the pathophysiology of detrusor overactivity. The present study aims to elucidate the signaling pathways of BK-induced detrusor muscle contraction, with the goal of better understanding the molecular regulation of micturition and identifying potential novel therapeutic targets of its disorders. Experiments have been carried out on bladders isolated from wild-type or genetically modified [smooth muscle-specific knockout (KO): Gαq/11-KO, Gα12/13-KO and constitutive KO: thromboxane prostanoid (TP) receptor-KO, cyclooxygenase-1 (COX-1)-KO] mice and on human bladder samples. Contractions of detrusor strips were measured by myography. Bradykinin induced concentration-dependent contractions in both murine and human bladders, which were independent of secondary release of acetylcholine, ATP, or prostanoid mediators. B2 receptor antagonist HOE-140 markedly diminished contractile responses in both species, whereas B1 receptor antagonist R-715 did not alter BK's effect. Consistently with these findings, pharmacological stimulation of B2 but not B1 receptors resembled the effect of BK. Interestingly, both Gαq/11- and Gα12/13-KO murine bladders showed reduced response to BK, indicating that simultaneous activation of both pathways is required for the contraction. Furthermore, the Rho-kinase (ROCK) inhibitor Y-27632 markedly decreased contractions in both murine and human bladders. Our results indicate that BK evokes contractions in murine and human bladders, acting primarily on B2 receptors. Gαq/11-coupled and Gα12/13-RhoA-ROCK signaling appear to mediate these contractions simultaneously. Inhibition of ROCK enzyme reduces the contractions in both species, identifying this enzyme, together with B2 receptor, as potential targets for treating voiding disorders.

NK2 receptor-mediated detrusor muscle contraction involves Gq/11-dependent activation of voltage-dependent Ca2+ channels and the RhoA-Rho kinase pathway.

Tachykinins (TKs) are involved in both the physiological regulation of urinary bladder functions and development of overactive bladder syndrome. The aim of the present study was to investigate the signal transduction pathways of TKs in the detrusor muscle to provide potential pharmacological targets for the treatment of bladder dysfunctions related to enhanced TK production. Contraction force, intracellular Ca2+ concentration, and RhoA activity were measured in the mouse urinary bladder smooth muscle (UBSM). TKs and the NK2 receptor (NK2R)-specific agonist [ß-Ala8]-NKA(4-10) evoked contraction, which was inhibited by the NKR2 antagonist MEN10376. In Gαq/11-deficient mice, [ß-Ala8]-NKA(4-10)-induced contraction and the intracellular Ca2+ concentration increase were abolished. Although Gq/11 proteins are linked principally to phospholipase Cß and inositol trisphosphate-mediated Ca2+ release from intracellular stores, we found that phospholipase Cß inhibition and sarcoplasmic reticulum Ca2+ depletion failed to have any effect on contraction induced by [ß-Ala8]-NKA(4-10). In contrast, lack of extracellular Ca2+ or blockade of voltage-dependent Ca2+ channels (VDCCs) suppressed contraction. Furthermore, [ß-Ala8]-NKA(4-10) increased RhoA activity in the UBSM in a Gq/11-dependent manner and inhibition of Rho kinase with Y-27632 decreased contraction force, whereas the combination of Y-27632 with either VDCC blockade or depletion of extracellular Ca2+ resulted in complete inhibition of [ß-Ala8]-NKA(4-10)-induced contractions. In summary, our results indicate that NK2Rs are linked exclusively to Gq/11 proteins in the UBSM and that the intracellular signaling involves the simultaneous activation of VDCC and the RhoA-Rho kinase pathway. These findings may help to identify potential therapeutic targets of bladder dysfunctions related to upregulation of TKs.