Botulinum toxin type A induces changes in the chemical coding of substance P-immunoreactive dorsal root ganglia sensory neurons supplying the porcine urinary bladder

Treating Lower Urinary Tract Symptoms in Older Adults: Intravesical Options

This article provides an overview of the diagnosis and the treatment of lower urinary tract symptoms in older adults complicated by the neurodegenerative changes in the micturition reflex and further confounded by age-related decline in hepatic and renal clearance raising the propensity of adverse drug reactions. The first-line drug treatment for lower urinary tract symptoms, orally administered antimuscarinics, fails to reach the equilibrium dissociation constant of muscarinic receptors even at their maximum plasma concentration and tends to evoke a half-maximal response at a muscarinic receptor occupancy of just 0.206% in the bladder with a minimal difference from exocrine glands, which raises the adverse drug reaction risk. On the contrary, intravesical antimuscarinics are instilled at concentrations 1000-fold higher than the oral maximum plasma concentration and the equilibrium dissociation constant erects a downhill concentration gradient that drives passive diffusion and achieves a mucosal concentration around ten-fold lower than the instilled concentration for a long-lasting occupation of muscarinic receptors in mucosa and sensory nerves. A high local concentration of antimuscarinics in the bladder triggers alternative mechanisms of action and is supposed to engage retrograde transport to nerve cell bodies for neuroplastic changes that underlie a long-lasting therapeutic effect, while an intrinsically lower systemic uptake of the intravesical route lowers the muscarinic receptor occupancy of exocrine glands to lower the adverse drug reaction relative to the oral route. Thus, the traditional pharmacokinetics and pharmacodynamics of oral treatment are upended by intravesical antimuscarinics to generate a dramatic improvement (~ 76%) noted in a meta-analysis of studies enrolling children with neurogenic lower urinary tract symptoms on the primary endpoint of maximum cystometric bladder capacity as well as the secondary endpoints of filling compliance and uninhibited detrusor contractions. The therapeutic success of intravesical multidose oxybutynin solution or oxybutynin entrapped in the polymer for sustained release in the pediatric population bodes well for patients with lower urinary tract symptoms at the other extreme of the age spectrum. Though generally used to predict oral drug absorption, Lipinski's rule of five can also explain the ten-fold lower systemic uptake from the bladder of positively charged trospium over oxybutynin, a tertiary amine. Chemodenervation by an intradetrusor injection of onabotulinumtoxinA is merited for patients with idiopathic overactive bladder discontinuing oral treatment because of a lack of efficacy. However, age-related peripheral neurodegeneration potentiates the adverse drug reaction risk of urinary retention that motivates the quest of liquid instillation, delivering larger fraction of onabotulinumtoxinA to the mucosa as opposed to muscle by an intradetrusor injection can also probe the neurogenic and myogenic predominance of idiopathic overactive bladder. Overall, the treatment paradigm of lower urinary tract symptoms in older adults should be tailored to individual's overall health status and the risk tolerance for adverse drug reactions.

Effect of Bladder Injection of OnabotulinumtoxinA on the Central Expression of Genes Associated with the Control of the Lower Urinary Tract: A Study in Normal Rats

To investigate a possible central mechanism of action of Botulinum toxin A (BoNT/A) following injection in the bladder, complementary to the acknowledged peripheral bladder effect, we studied changes in the expression of neuropeptides and receptors involved in lower urinary tract function in the spinal cord (SC) and dorsal root ganglia (DRG) of normal rats following BoNT/A bladder injection. Thirty-six Sprague-Dawley rats, divided into three groups of n = 12, received bladder injections of 2U or 5U OnabotulinumtoxinA (BOTOX^®), or saline. Six animals from each group were sacrificed on days 7 and 14. Expression of Tachykinin 1 (Tac1), capsaicin receptor (TRPV1), neuropeptide Y (NPY), proenkephalin (PENK) and muscarinic receptors M1, M2, M3, was evaluated in the bladder, L6-S1 DRG, and SC segments using real-time PCR and Western blotting. Real-time PCR revealed increased expression of NPY in all tissues except for SC, and increased TRPV1 and PENK expression in DRG and SC, whereas expression of Tac1, M1 and M2 was decreased. Less significant changes were noted in protein levels. These findings suggest that bladder injections of OnabotulinumtoxinA may be followed by changes in the expression of sensory, sympathetic and cholinergic bladder function regulators at the DRG/SC level.

The Role of Physiotherapy in the Management of Functional Neurological Disorder in Children and Adolescents

Children and adolescents with functional neurological (conversion) disorder (FND) present with symptoms of impaired motor and sensory function. FND involves complex interactions between the brain, mind, body, and lived experience of the child. The gold standard for treatment is therefore a holistic, biopsychosocial approach with multimodal interventions delivered by a multidisciplinary team. In this narrative review we examine the role of physiotherapy in managing FND in children. We searched Embase, Medline, PsycINFO, and PubMed (back to 2000) for relevant physiotherapy articles and also manually searched their reference lists. Two review articles and ten observational studies were identified. Data were extracted concerning the type of study, therapies involved, outcome measures, and comorbid mental health outcomes. FND symptoms resolved in 85% to 95% of the patients, and about two-thirds returned to full-time school after completing the multidisciplinary intervention. Ongoing mental health concerns at follow-up were associated with poorer functional outcomes. Key themes included the following: use of psychological interventions embedded in the physiotherapy intervention; integration of play, music, and dance; role of physical exercise in modulating physiological, neural, and endocrine systems; need for FND-specific outcome measures; ethical issues pertaining to randomized trials; and need to develop alternate study methodologies for assessing combined treatments. Clinical vignettes were included to highlight a range of physiotherapy interventions. In conclusion, the emerging literature suggests that physiotherapy for children with FND is a useful intervention for improving motor dysfunction and for addressing other concurrent issues such as physical deconditioning, neuroprotection, chronic pain, disturbed sleep, anxiety and depression, and resilience building.

The Influence of an Adrenergic Antagonist Guanethidine (GUA) on the Distribution Pattern and Chemical Coding of Dorsal Root Ganglia (DRG) Neurons Supplying the Porcine Urinary Bladder

Although guanethidine (GUA) was used in the past as a drug to suppress hyperactivity of the sympathetic nerve fibers, there are no available data concerning the possible action of this substance on the sensory component of the peripheral nervous system supplying the urinary bladder. Thus, the present study was aimed at disclosing the influence of intravesically instilled GUA on the distribution, relative frequency, and chemical coding of dorsal root ganglion neurons associated with the porcine urinary bladder. The investigated sensory neurons were visualized with a retrograde tracing method using Fast Blue (FB), while their chemical profile was disclosed with single-labeling immunohistochemistry using antibodies against substance P (SP), calcitonin gene-related peptide (CGRP), pituitary adenylate cyclase activating polypeptide (PACAP), galanin (GAL), neuronal nitric oxide synthase (nNOS), somatostatin (SOM), and calbindin (CB). After GUA treatment, a slight decrease in the number of FB⁺ neurons containing SP was observed when compared with untreated animals (34.6 ± 6.5% vs. 45.6 ± 1.3%), while the number of retrogradely traced cells immunolabeled for GAL, nNOS, and CB distinctly increased (12.3 ± 1.0% vs. 7.4 ± 0.6%, 11.9 ± 0.6% vs. 5.4 ± 0.5% and 8.6 ± 0.5% vs. 2.7 ± 0.4%, respectively). However, administration of GUA did not change the number of FB⁺ neurons containing CGRP, PACAP, or SOM. The present study provides evidence that GUA significantly modifies the sensory innervation of the porcine urinary bladder wall and thus may be considered a potential tool for studying the plasticity of this subdivision of the bladder innervation.

The effect of botulinum toxin on ureteral inflammation

PURPOSE

The impact of onabotulinum toxin type A (BoNT-A) on bladder afferent nerve pathways and chemosensory functions is an active area of investigation. There may be a role for BoNT-A in disorders of the ureter; however, no histologic studies have assessed the effects of BoNT-A on ureteral tissue. Our objective was to develop an animal model of ureteral inflammation and determine the impact of ureteral BoNT-A instillation on known mechanisms of inflammation.

METHODS

The safety and feasibility of a novel animal model of ureteral inflammation was assessed. Through open cystotomy, the effect of ureteral BoNT-A instillation on inflammation was determined through H&E, masson's trichrome, Ki-67 stain, and prostaglandin E (PGE) synthase expression, a known marker of pain and inflammation in ureteral tissue. Urothelial microstructure was assessed using electron microscopy and standard histologic techniques.

RESULTS

All experiments were carried to completion, and no systemic signs of botulinum toxicity were seen. BoNT-A exposure was associated with a decrease in PGE synthase expression in a dose-dependent fashion. BoNT-A exposure was not found to impact collagen deposition or cell proliferation. Disruption of tight junctions between urothelial cells was observed under conditions of inflammation.

CONCLUSION

We describe the feasibility of a novel in vivo model of ureteral inflammation and report the first histologic study of the effects of BoNT-A on the ureter. Preliminary findings show that BoNT-A attenuates ureteral PGE synthase expression under conditions of inflammation. The application of BoNT-A may provide anti-inflammatory and analgesic effects in the context of ureteral disorders.

Endometritis affects chemical coding of the dorsal root ganglia neurons supplying uterus in the sexually mature gilts

This study reports on the influence of experimentally-induced uterine inflammation on chemical phenotypes, number and distribution of neurons in the dorsal root ganglia (DRGs) innervating the uterus in sexually mature gilts. On day 17 of the first studied estrous cycle, the uterine horns were injected with retrograde tracer Fast Blue (FB). After 28 days (on an expected day 3 of third studied estrous cycle), 50 ml of either saline (group SAL) or Escherichia coli (E. coli) suspension (10⁹ colony-forming units/ml, group E. coli) were injected into each uterine horn. In the control pigs (group CON), only laparotomy was performed. Eight days later DRGs and uteri were collected. All infected gilts developed severe form of acute endometritis. By use of double immunofluorescence labelling the numbers of uterine perikarya expressing substance P (SP), calcitonin gene-related peptide (CGRP), neurokinin A (NKA), galanin (GAL) and pituitary adenylate cyclase-activating polypeptide (PACAP) were analyzed. Injection of E. coli decreased the total number of the FB positive perykaria in the Th10-S4 DRGs. We revealed an increase in the populations of uterine perikarya coded SP⁺/CGRP^-, SP⁺/NKA^-, SP^-/NKA⁺, SP⁺/GAL⁺, SP⁺/GAL^-, SP^-/GAL⁺, SP⁺/PACAP⁺ and SP^-/PACAP⁺. Our results suggest that uterine inflammation affects both the spatial and neurochemical organization pattern of uterine sensory innervation. Additionally, the inflammation may affect the transmission of sensory information from uterus to spinal cord.

Distribution and neurochemistry of porcine urinary bladder-projecting sensory neurons in subdomains of the dorsal root ganglia: A quantitative analysis

The aim of the present study has been to verify the inter- and intraganglionic distribution pattern of porcine urinary bladder-projecting (UBP) neurons localized in the sacral dorsal root ganglia (DRGs). The morphology and chemical phenotype of these cells have also been investigated. These neurons were visualized using the fluorescent tracer Fast Blue (FB) which was injected bilaterally into the urinary bladder wall of five juvenile female pigs. The intraganglionic distribution showed that small- and medium-sized FB+ perikarya were mainly located in the central (S₃-S₄) and periphero-central (S₂) region of the ganglia, while large cells were heterogeneously distributed. Immunohistochemistry revealed that the most frequently observed markers in small and medium-sized UBP perikarya were: neurofilament 200, lectin from Bandeiraea simplicifolia (Griffonia simplicifolia) isolectin B4, substance P, calcitonin gene-related peptide, pituitary adenylate cyclase-activating polypeptide and transient receptor potential vanilloid 1. Moreover, UBP neurons containing these substances were also mainly observed in the central and periphero-central region of the ganglion. Differences in the percentage of traced cells and their neuropeptide content were observed between the S₂, S₃ and S₄ DRGs. In conclusion, the present study, for the first time, describes the arrangement of UBP DRGs neurons within particular subdomains of sacral ganglia, taking into account their size and chemical phenotype.

IncobotulinumtoxinA Injection for Temporomandibular Joint Disorder

OBJECTIVES

Temporomandibular disorder (TMD) involves dysfunction of the temporomandibular joint and associated muscles of mastication causing pain with chewing, limitation of jaw movement, and pain. While the exact pathophysiology of TMD is not completely understood, it is thought that hyperfunction of the muscles of mastication places stress on the temporomandibular joint, leading to degeneration of the joint and associated symptoms. We hypothesize that chemodenervation of the muscles of mastication with IncobotulinumtoxinA (Xeomin) will decrease the stress on the temporomandibular joint and improve pain associated with temporomandibular joint and muscle disorder (TMJD).

METHODS

Twenty patients were randomized to IncobotulinumtoxinA (170 units) or saline injection of the masticatory muscles. Patient-reported pain scale (0-10) was recorded at 4-week intervals following injection for 16 weeks. Patients who received saline injection initially were assessed for reduction in pain at the first 4-week interval and if still had significant pain were rolled over into the IncobotulinumtoxinA arm.

RESULTS

Preinjection pain scores were similar between patients. While there was a statistically significant reduction in pain score in the placebo group one month, there was an overall larger drop in average pain scores in those patients injected with IncobotulinumtoxinA initially. All patients initially injected with placebo crossed over into the IncobotulinumtoxinA group. Similar results were seen when examining the composite masticatory muscle tenderness scores. There was no significant change in usage of pain medication.

CONCLUSIONS

We demonstrate utility of IncobotulinumtoxinA in treating patients with TMD with pain despite pain medication usage and other conventional treatments.