Age mediated effects of oxytocin antagonists on tension in the rat bladder: An organ bath evaluation

Badshah M1, Ibrahim J2, Su N3, Middendorff R4, Whittaker M5, Exintaris B3

Research Type

Pure and Applied Science / Translational

Abstract Category

Male Lower Urinary Tract Symptoms (LUTS) / Voiding Dysfunction

Abstract 78
Open Discussion ePosters
Scientific Open Discussion Session 7
Thursday 8th September 2022
12:40 - 12:45 (ePoster Station 1)
Exhibition Hall
Detrusor Overactivity Hormone Therapy Animal Study Male Overactive Bladder
1. Hudson Department of Molecular and Translational Sciences, Monash University, Australia, 2. School of Biomedical Sciences, University of Queensland, Australia, 3. Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Australia, 4. Institute of Anatomy and Cell Biology, Justus Liebig University, Germany, 5. Drug Delivery Disposition and Dynamics, Monash Institute of Pharmaceutical Sciences, Australia
Online
Presenter
M

Masroor Badshah
Hudson Department of Molecular and Translational Sciences, Monash University, Australia
Links

Poster

Abstract

Hypothesis / aims of study 
Recent evidence suggests that oxytocin signalling, which is involved in cellular proliferation, cellular differentiation and smooth muscle contraction within the bladder, might have an association with an overactive bladder (OAB, Urgency) syndrome [1, 2]. In particular, the neuropeptide oxytocin may exacerbate changes in urinary behaviour causing an upregulation of oxytocin receptors (OXTRs), resulting in an increase in basal tension (myogenic tone) within the bladder. Therefore, we hypothesise that targeting OXTRs within the bladder using oxytocin antagonists such as atosiban, cligosiban & ß-mercapto-ß,ßcyclopentamethylenepropionyl (ßMßßC) may decrease myogenic tone, thus providing a new therapeutic avenue for the treatment of OAB.
Study design, materials and methods 
Young (7-9 weeks) and older (4-9 months) Sprague Dawley healthy male rats (n=5, each group) were placed in carbon dioxide (CO2) chamber and euthanized by CO2 inhalation. An incision in the abdomen was made along the midline to expose the urogenital organs and isolate the bladder. Bladders were dissected into two equal length perpendicular strips and stored in minimal essential medium (MEM) (Thermo Fisher Scientific, Waltham, MA, USA). Tissues were then mounted in an organ bath apparatus containing fresh Krebs-Henseleit solution under 0.5-1g of tension. Evaluation of tissue contractility using high concentration of potassium (Hi-K+) was then conducted pre and post incubation with atosiban, cligosiban and ßMßßC. Data generated was exported from lab charts to excel spreadsheet which was then analysed using GraphPad Prism software (version 9; GraphPad Software, La Jolla, CA, USA).
Results 
In this study, oxytocin (OT) (1µM) significantly increased bladder contraction in both young and older rats. OT induced contractions were significantly inhibited by ßMßßC (1µM) and  atosiban (^5M) in both aged group rats (p < 0.0001). OT induced contractions were also inhibited in young rats but not older rats in response to low concentrations (1µM) of atosiban (p < 0.05). Interestingly, cligosiban was only observed to inhibit OT induced contractions in older rats at higher concentrations (^5M) (p < 0.05).
Interpretation of results 
These findings reveal that there are age and concentration mediated differences in drugs efficacy. This is the first study that compares the effect of the three antagonists (ßMßßC, atosiban and cligosiban) on oxytocin induced contraction within the rat bladder.
Concluding message 
This study indicates that oxytocin can induce contractility in bladder smooth muscle from young and older rats. While oxytocin receptor antagonists such as ßMßßC, atosiban and cligosiban are capable of inhibiting OT induced contractions, there appears to be greater sensitivity to ßMßßC across ages. This suggests  ßMßßC could be a promising drug candidate for the treatment of overactive bladder. Further studies are ongoing to determine the role of OXTRs within the bladder, to improve our understanding of OAB and to explore future therapeutic opportunities.
Figure 1 Application of ßMßßC(1µM), an oxytocin receptor antagonist significantly decreased oxytocin induced bladder contraction in 7-9 weeks Sprague Dawley healthy male rats (****p < 0.0001, significant, 2-way ANOVA Sidak’s multiple comparisons test).
Figure 2 A substantial effect of ßMßßC(1µM), an oxytocin receptor antagonist on oxytocin induced bladder contraction (1µM) in 4-9 months Sprague Dawley healthy male rats (****p < 0.0001, significant, 2-way ANOVA Sidak’s multiple comparisons test).
References 
  1. Romine, M.T. and G.F. Anderson, Evidence for oxytocin receptors in the urinary bladder of the rabbit. Canadian Journal of Physiology and Pharmacology, 1985. 63(4): p. 287-291.
  2. Pandita, R., A. Nylen, and K.-E. Andersson, Oxytocin-induced stimulation and inhibition of bladder activity in normal, conscious rats—influence of nitric oxide synthase inhibition. Neuroscience, 1998. 85(4): p. 1113-1119.
Disclosures
Funding Funding was granted by the Monash University, Australia and Deutsche Forschungsgemeinschaft (GRK 1871) to the International Research Training Group (IRTG), a joint collaboration between Monash university, Australia and Justus Liebig university Germany. M.Badshah was supported by Monash Graduate Scholarship (MGS) and Monash Departmental Scholarship (MDS). Clinical Trial No Subjects Animal Species Sprague Dawley Male Rats Ethics Committee Animal Ethics Committee Monash Animal Research Platform, Monash University, Victoria, Australia (Ethical Approval No. 00000).
08/05/2025 18:46:43