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Bladder Smooth Muscle Strip Contractility as a Method to Evaluate Lower Urinary Tract Pharmacology
Published on: August 18, 2014
Targets for botulinum toxin in the lower urinary tract
1Department of Urology and IBMC, Hospital de São João and Faculty of Medicine of Porto, Porto, Portugal.
Neurourology and Urodynamics
|June 19, 2013
Summary
Botulinum toxin type A (BoNT/A) affects neurotransmitter release from bladder nerve fibers and urothelial cells. Its precise mechanism and optimal application require further investigation.
Area of Science:
- Urology
- Neuroscience
- Pharmacology
Background:
- Botulinum toxin type A (BoNT/A) is a widely used neurotoxin, with OnabotulinumtoxinA being the most studied brand.
- BoNT/A targets synaptosome-associated protein 25 kDa (SNAP-25), a key protein in synaptic vesicle fusion.
- Dose equivalence studies between different BoNT/A brands are lacking.
Purpose of the Study:
- To review the current literature on the mechanisms of action of Botulinum toxin type A (BoNT/A).
- To provide updated knowledge on how BoNT/A affects neuronal and cellular functions relevant to its therapeutic applications.
Main Methods:
- A comprehensive literature review was conducted.
- The review focused on studies detailing the mechanisms of botulinum toxin action.
Main Results:
- BoNT/A cleaves SNAP-25 in parasympathetic, sympathetic, and sensory nerve fibers, reducing neurotransmitter release (acetylcholine, norepinephrine, glutamate, neuropeptides).
- While not directly affecting urothelium or myofibroblasts, BoNT/A decreases ATP and neurotrophin release from urothelial cells.
- BoNT/A does not induce apoptosis in the bladder but has been shown to induce apoptosis in prostate cells.
Conclusions:
- BoNT/A's mechanism in the bladder involves neurotransmitter release from both nerve fibers and urothelial cells.
- The relative importance of specific neurotransmitters and factors like injection volume and site require further research.
- The long-term effects and optimal application strategies for BoNT/A in urological treatments need additional evaluation.
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