OnabotulinumtoxinA significantly attenuates bladder afferent nerve firing and inhibits ATP release from the urothelium

Abstract

Objective• To investigate the direct effect of onabotulinumtoxinA (OnaBotA) on bladder afferent nerve activity and release of ATP and acetylcholine (ACh) from the urothelium. Materials and Methods• Bladder afferent nerve activity was recorded using an in vitro mouse preparation enabling simultaneous recordings of afferent nerve firing and intravesical pressure during bladder distension.• Intraluminal and extraluminal ATP, ACh, and nitric oxide (NO) release were measured using the luciferin-luciferase and Amplex ® Red assays (Molecular Probes, Carlsbad, CA, USA), and fluorometric assay kit, respectively.• OnaBotA (2U), was applied intraluminally, during bladder distension, and its effect was monitored for 2 h after application.• Whole-nerve activity was analysed to classify the single afferent units responding to physiological (low-threshold [LT] afferent <15 mmHg) and supra-physiological (high-threshold [HT] afferent >15 mmHg) distension pressures. Results• Bladder distension evoked reproducible pressure-dependent increases in afferent nerve firing.• After exposure to OnaBotA, both LT and HT afferent units were significantly attenuated.• OnaBotA also significantly inhibited ATP release from the urothelium and increased NO release. Conclusion• These data indicate that OnaBotA attenuates the bladder afferent nerves involved in micturition and bladder sensation, suggesting that OnaBotA may exert its clinical effects on urinary urgency and the other symptoms of overactive bladder syndrome through its marked effect on afferent nerves.

The purinergic neurotransmitter revisited: A single substance or multiple players?

“…Urothelial ATP release following mechanical stretch shows greater sensitivity to TTX in bladders from patients with neurogenic detrusor overactivity (Kumar et al, 2010), suggesting that this condition might be associated with increased release of ATP from neuronal sources. In a recent study, intravesical instillation of onabotulinumtoxin A in distended mouse bladder inhibited ATP release from the urothelium, but the site of action of this neurotoxin was not determined (Collins et al, 2013). Interestingly, the concentrations of ATP in the bladder lumen are lower in patients with refractory overactive bladder with bacteriuria than in patients without bacteriuria, but the underlying mechanisms are currently unknown (Walsh et al, 2013).…”

Pirt reduces bladder overactivity by inhibiting purinergic receptor P2X3

“…GFP-tagged P2X3 was constructed by subcloning the full-length P2X3 cDNA into a pEGFP-N2 vector (Clontech). HA-tagged Pirt and PirtD (2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14) were constructed by subcloning the full-length or truncated Pirt cDNA into the pCMV-HA vector (Clontech). Full-length P2X3 cDNA was also subcloned into pcDNA3.1 3.1/myc-His( À ) A (Invitrogen).…”

“…In response to physical and chemical stimulation, the urothelium releases several substances, including acetylcholine, ATP, prostaglandins and so on [6][7][8] . These chemical agents modify afferent nerve activity and sensation in the suburothelial layer and in the muscle layer 2 .…”

Clinical comparison of botulinum toxin in motor and autonomic disorders: Similarities and differences

“…Indeed, a marked effect on bladder afferent nerve fiber activity has been recorded in an animal model after intraluminal application of BoNT (Collins et al, 2013). Bladder distension evoked activity in afferent nerves was significantly attenuated after onabotulinum toxin A. BoNT significantly inhibited ATP release from urothelium and increased NO release.…”