Mechanisms inducing autonomic dysreflexia during urinary bladder distention in rats with spinal cord injury

Intravesical injection of botulinum toxin type a may be an effective treatment option for autonomic dysreflexia in patients with high-level spinal cord injury

OBJECTIVE

To evaluate the efficacy of intravesical injection of botulinum toxin type A (BTX-A) for neurogenic detrusor overactivity (DO) in reducing the frequency and severity of autonomic dysreflexia (AD).

DESIGN

A cross-sectional nonrandomized trial with before (baseline) and after (follow-up) assessments.

SETTING

A single spinal cord injury (SCI) rehabilitation center in China.

PARTICIPANTS

Twenty-five patients with SCI at or above T6 and a history of AD who underwent urodynamic studies (UDS) before and 3 months after BTX-A injection.

INTERVENTIONS

Received bladder injection treatment wtih 200 U BTX-A.

OUTCOME MEASURES

The maximum detrusor pressure(Pdetmax) and voume at first DO(VFIDC), baseline and overall maximum systolic blood pressure (SBP) during UDS, and scores of Incontinence Specific Quality of Life Instrument (IQoL) were recorded before and 3 months after the injection. The change in SBP (ΔSBP) from baseline to maximum SBP during UDS was calculated to assess the severity. The frequency of AD was recorded using ambulatory blood pressure monitoring during a 24 h period before and 3 months after the injection.

RESULTS

BTX-A injection decreased the Pdetmax and increased the VFIDC and mean urine volume per catheterization increased. The maximum SBP and the ΔSBP during UDS decreased significantly decreased after the injection (151.44 ± 13.92 vs 133.32 ± 9.20 mmHg and 49.44 ± 12.81 vs 33.08 ± 9.11 mmHg respectively, P < 0.05). The frequency of bladder-related ADs (i.e. performed a clean intermittent catheterization or leakage) during a 24-h period significantly decreased from 11.04 ± 1.81-7.88 ± 2.15 (P < 0.001).

CONCLUSIONS

BTX-A decreases the severity of SBP increase and the number of AD episodes 3 months after intravesical injection.

Using uniaxial tensile testing to evaluate the biomechanical properties of bladder tissue after spinal cord injury in rat model

To investigate the biomechanical properties of rat bladder tissue after spinal cord injury (SCI) using uniaxial tensile testing. Evidence suggests the bladder wall undergoes remodeling following SCI. There is limited data describing the biomechanical properties of bladder wall after SCI. This study describes the changes in elastic and viscoelastic mechanical properties of bladder tissue using a rat model after SCI. Seventeen adult rats received mid-thoracic SCI. Basso, Beattie, and Bresnahan (BBB) locomotor testing was performed on the rats 7-14 days after injury quantifying the degree of SCI. Bladder tissue samples were collected from controls and spinal injured rats at 2- and 9-weeks post-injury. Tissue samples underwent uniaxial stress relaxation to determine instantaneous and relaxation modulus as well as monotonic load-to failure to determine Young's modulus, yield stress and strain, and ultimate stress. SCI resulted in abnormal BBB locomotor scores. Nine weeks post-injury, instantaneous modulus decreased by 71.0% (p = 0.03) compared to controls. Yield strain showed no difference at 2 weeks post-injury but increased 78% (p = 0.003) in SCI rats at 9 weeks post-injury. Compared to controls, ultimate stress decreased 46.5% (p = 0.05) at 2 weeks post-injury in SCI rats but demonstrated no difference at 9 weeks post-injury. The biomechanical properties of rat bladder wall 2 weeks after SCI showed minimal difference compared to controls. By week 9, SCI bladders had a reduction in instantaneous modulus and increased yield strain. The findings indicate biomechanical differences can be identified between control and experimental groups at 2- and 9-week intervals using uniaxial testing.

Histopathological Evaluation of Spinal Cord with Experimental Traumatic Injury Following Implantation of a Controlled Released Drug Delivery System of Chitosan Hydrogel Loaded with Selenium Nanoparticle

The purpose of this study was to evaluate the neuroprotective effect of local implantation of a controlled delivery system of chitosan hydrogel loaded with selenium nanoparticles in rats with spinal cord injury (SCI). For this purpose, 60 adult female rats were randomly divided into three equal groups. In all three groups, SCI was induced by aneurysm clamping at the level of thoracic vertebrae under inhaled anesthesia with isoflurane. In one group after spinal cord injury, chitosan hydrogels loaded with selenium nanoparticles (treatment group), and in the other group, only chitosan hydrogels (positive control group) were placed at the site of injury. In the last group (negative control), no material was placed in the injury site. Hematoxylin-eosin and glial fibrillary acidic protein (GFAP) staining evaluated histological changes at the site of injury on days 3, 7, 21, and 28 after surgery. Evaluations show that hemorrhage and inflammation also have a marked decrease in inflammatory cells at different times in the treatment group. This decrease was also seen in the chitosan group but was less severe than in the treatment group. The formation of nerve fibers was also observed in the treatment group over time of injury. Immunohistochemical studies of damaged tissue showed higher expression of GFAP protein in the astrocytes of the treatment group than in the other two groups and the chitosan group compared with the negative control group. A controlled drug delivery system containing selenium nanoparticles seems to play a role in the protection of nerve cells through its anti-inflammatory effect.

Effects of early intravesical administration of resiniferatoxin to spinal cord-injured rats in neurogenic detrusor overactivity

OBJECTIVES

To investigate if intravesical administration during spinal shock of resiniferatoxin (RTX), an ultrapotent desensitizing agonist of transient receptor potential vanilloid-1 (TRPV1), would silence TRPV1-expressing bladder afferents at an early stage of disease progression and modulate neurogenic detrusor overactivity (NDO) emergence.

MATERIALS AND METHODS

Rats submitted to largely incomplete spinal cord transection at T8/9 spinal segment were treated with intravesical RTX (50 nM) or its vehicle during spinal shock. Four weeks after spinal lesion, bladder-reflex activity was evaluated by cystometry under urethane anesthesia, after which the bladder, spinal cord, and dorsal root ganglia were collected and processed.

RESULTS

We found improvements on bladder function several weeks after early intravesical RTX administration, including a marked decrease of intravesical pressures and amplitude of bladder contractions. Such strong long-lasting urodynamic effects resulted from the very potent desensitizing activity of RTX on peripheral terminals of sensory afferents, an effect restricted to the bladder.

CONCLUSION

Our results support that an early intervention with RTX could potentially attenuate NDO development and ensuing urinary incontinence, with a dramatic impact on the quality of life of spinal cord injury patients.

The effect of neutralization of nerve growth factor (NGF) on bladder and urethral dysfunction in mice with spinal cord injury

AIMS

To investigate the role of nerve growth factor (NGF) in lower urinary tract dysfunction in mice with spinal cord injury (SCI).

METHODS

Using 4-week SCI mice, single-filling cystometry and external urethral sphincter (EUS)-electromyography were performed under an awake condition. In some SCI mice, anti-NGF antibodies (10 µg/kg/h) were administered for 1 or 2 weeks before the urodynamic study. NGF levels in the bladder and L6/S1 spinal cord were assayed by ELISA. The transcript levels of P2X receptors and TRP channels in L6/S1 dorsal root ganglia (DRG) were measured by RT-PCR.

RESULTS

In SCI mice, the area under the curve of non-voiding contractions (NVCs) during the storage phase was significantly decreased in both 1- and 2-week anti-NGF antibody-treated SCI groups. However, EUS-electromyogram parameters during voiding were not altered by the treatment. Bladder mucosal and spinal NGF levels were decreased after 2 weeks of anti-NGF antibody treatment. TRPA1 and TRPV1 transcripts in L6/S1 DRG were significantly decreased after 1- or 2-week anti-NGF treatment.

CONCLUSIONS

In SCI mice, NGF is involved in the emergence of NVCs in association with increased expression of TRP receptors that are predominantly found in C-fiber afferent pathways. Thus, NGF targeting treatments could be effective for treating storage problems such as detrusor overactivity after SCI.

Drug Targets in Neurotrophin Signaling in the Central and Peripheral Nervous System

Neurotrophins are a family of proteins that play an important role in the regulation of the growth, survival, and differentiation of neurons in the central and peripheral nervous system. Neurotrophins were earlier characterized by their role in early development, growth, maintenance, and the plasticity of the nervous system during development, but recent findings also indicate their complex role during normal physiology in both neuronal and non-neuronal tissues. Therefore, it is important to recognize a deficiency in the expression of neurotrophins, a major factor driving the debilitating features of several neurologic and psychiatric diseases/disorders. On the other hand, overexpression of neurotrophins is well known to play a critical role in pathogenesis of chronic pain and afferent sensitization, underlying conditions such as lower urinary tract symptoms (LUTS)/disorders and osteoarthritis. The existence of a redundant receptor system of high-and low-affinity receptors accounts for the diverse, often antagonistic, effects of neurotrophins in neurons and non-neuronal tissues in a spatial and temporal manner. In addition, studies looking at bladder dysfunction because of conditions such as spinal cord injury and diabetes mellitus have found alterations in the levels of these neurotrophins in the bladder, as well as in sensory afferent neurons, which further opens a new avenue for therapeutic targets. In this review, we will discuss the characteristics and roles of key neurotrophins and their involvement in the central and periphery nervous system in both normal and diseased conditions.

Morphological changes in different populations of bladder afferent neurons detected by herpes simplex virus (HSV) vectors with cell-type-specific promoters in mice with spinal cord injury

Functional and morphological changes in C-fiber bladder afferent pathways are reportedly involved in neurogenic detrusor overactivity (NDO) after spinal cord injury (SCI). This study examined the morphological changes in different populations of bladder afferent neurons after SCI using replication-defective herpes simplex virus (HSV) vectors encoding the mCherry reporter driven by neuronal cell-type-specific promoters. Spinal intact (SI) and SCI mice were injected into the bladder wall with HSV mCherry vectors driven by the cytomegalovirus (CMV) promoter, CGRP promoter, TRPV1 promoter or neurofilament 200 (NF200) promoter. Two weeks after vector inoculation into the bladder wall, L1 and L6 dorsal root ganglia (DRG) were removed bilaterally for immunofluorescent staining using anti-mCherry antibody. The number of CMV promoter vector-labeled neurons was not altered after SCI. The number of CGRP and TRPV1 promoter vector-labeled neurons was significantly increased whereas the number of NF200 vector-labeled neurons was decreased in L6 DRG after SCI. The median size of CGRP promoter-labeled C-fiber neurons was increased from 247.0 in SI mice to 271.3μm² in SCI mice whereas the median cell size of TRPV1 promoter vector-labeled neurons was decreased from 245.2 in SI mice to 216.5μm² in SCI mice. CGRP and TRPV1 mRNA levels of laser-captured bladder afferent neurons labeled with Fast Blue were significantly increased in SCI mice compared to SI mice. Thus, using a novel HSV vector-mediated neuronal labeling technique, we found that SCI induces expansion of the CGRP- and TRPV1-expressing C-fiber cell population, which could contribute to C-fiber afferent hyperexcitability and NDO after SCI.

Effects of liposome-based local suppression of nerve growth factor in the bladder on autonomic dysreflexia during urinary bladder distention in rats with spinal cord injury

PURPOSE

To examine (1) whether spinal cord injury (SCI) time-dependently increases the severity of autonomic dysreflexia (AD) and expression levels of bladder nerve growth factor (NGF) protein, and (2) whether local suppression of NGF in the bladder improves SCI-induced AD in rats.

MATERIALS AND METHODS

SCI was produced by the transection of the T2/3 spinal cord in female Sprague-Dawley rats. At 4 or 8weeks after SCI, differences in the mean arterial blood pressure (ΔMAP) and heart rate (ΔMHR) during graded increases in intravesical pressure to 20, 40 and 60cm H₂O from those before bladder distention and NGF protein levels in the bladder wall were evaluated in spinal intact and SCI rats under urethane anesthesia. Seven weeks after SCI liposome-NGF antisense conjugates were administered intravesically to the animals. At 1week after intravesical treatment (8weeks after SCI), ΔMAP and ΔMHR during bladder distention and bladder NGF protein expression were evaluated.

RESULTS

The ΔMAP and ΔMHR were increased in a graded manner in response to bladder distention at intravesical pressures of 20, 40 and 60cm H₂O in SCI rats. These AD-like cardiovascular responses and NGF protein expression in the bladder mucosal and muscle layers were increased after SCI in a time-dependent manner. The liposome-NGF antisense treatment significantly reduced the NGF protein overexpression in the mucosal layer of SCI rat bladder and reduced ΔMAP and ΔMHR elicited by bladder distention.

CONCLUSIONS

These results indicate that the duration of the post-SCI recovery period affects the severity of AD induced by bladder distention as well as the level of bladder NGF protein, and that local suppression of NGF expression in the bladder reduces SCI-induced AD. Thus, Intravesical application of liposome-NGF antisense conjugates can be a new effective therapy for bladder distention-induced AD after SCI.

Effect of imidafenacin on the urodynamic parameters of patients with indwelling bladder catheters due to spinal cord injury

STUDY DESIGN

A retrospective study.

OBJECTIVES

To investigate the effect of imidafenacin on the urodynamic parameters of patients with indwelling bladder catheters due to spinal cord injury (SCI).

SETTING

Spinal center (Tokyo, Japan).

METHODS

Imidafenacin was prescribed to 34 patients with SCI who had a low cystometric volume and/or detrusor compliance according to a urodynamic study. A low cystometric volume and detrusor compliance were defined as <200 ml and <20 ml cm-1 H2O, respectively. The urodynamic study was repeated 4 weeks after imidafenacin was prescribed. When the urodynamic parameters did not improve in the follow-up study, the dose of imidafenacin was increased twofold. Then the urodynamic study was repeated 4 weeks thereafter. We compared the urodynamic parameters before and after imidafenacin treatment. Complications such as vesico-urethral reflux (VUR) and autonomic dysreflexia (AD) were documented.

RESULTS

Fifteen patients took 0.2 mg of imidafenacin daily, and 19 received 0.4 mg of imidafenacin daily. Imidafenacin increased the cystometric volume from 246.0 to 321.5 ml (median, P=0.002), detrusor compliance from 6.67 ml cm-1 H2O to 8.98 ml cm-1 H2O (median, P=0.012), and decreased the detrusor pressure from 37.0 cm H2O to 30.5 cm H2O (median, P=0.056). All three patients who had VUR fully recovered. Although 3 of 12 patients recovered from AD, 3 patients newly developed symptoms of AD. No patient withdrew from treatment due to adverse effects.

CONCLUSION

Imidafenacin is a safe drug that may improve the urodynamic parameters of patients with SCI, and it possibly alleviates bladder complications.

Intravesical Botulinum Toxin for Persistent Autonomic Dysreflexia in a Pediatric Patient

Introduction. We present a novel case of persistent autonomic dysreflexia in a pediatric spinal cord injury patient treated successfully with intravesical botulinum toxin. Study Design. A retrospective chart review of one patient seen at the Children's Hospital of Wisconsin from 2006 to 2012 was performed. Results. A pediatric spinal cord injury patient with known neurogenic bladder presented with severe hypertension consistent with autonomic dysreflexia. His symptoms and hypertension did not improve with conservative measures, and he necessitated ICU admission and antihypertensive drips. He was taken to the operating room for intravesical botulinum toxin for refractory bladder spasms. Following this, his symptoms abated, and he was weaned off IV antihypertensives and returned to his baseline state. His symptoms were improved for greater than six months. Conclusions. There are few treatment options for the management of refractory autonomic dysreflexia. Intravesical botulinum toxin has never been reported for this use. Dedicated research is warranted to assess its efficacy, as it was used successfully to abort autonomic dysreflexia in this patient.

Spontaneous Recovery of Reflex Voiding Following Spinal Cord Injury Mediated by Anti-inflammatory and Neuroprotective Factors

OBJECTIVE

To investigate the time-dependent changes in expression of cytokines that characterizes the spontaneous recovery of reflex voiding after spinal cord injury (SCI). SCI is known to reorganize the neural circuitry of micturition reflex after injury.

METHODS

Under isoflurane anesthesia, spinal cord of 18 adult female Sprague-Dawley rats was completely transected at the Th9-10 level. Awake cystometry was performed at each time point on controls and 6 SCI animals, and bladder was then harvested for analysis of 29 proteins Millipore kit or enzyme-linked immunosorbent assay. Prophylactic dose of ampicillin 100 mg/kg was administered periodically to all SCI animals.

RESULTS

Spontaneous recovery of voiding after SCI at 12 weeks was evident from increased intercontractile interval and voiding efficiency during cystometry. Expression of proinflammatory interleukins ([IL] IL-1α and IL-1β, IL-2, IL-5, IL-6, IL-18, tumor necrosis factor alpha [TNF-α]) and CXC chemokines (CXCL1, CXCL2, CXCL10), CX3CL1, and CCL2 showed significant elevation at 4 and at 8 weeks with slight decrease at 12 weeks. In contrast, expression of anti-inflammatory IL-10 and neuroprotective factors, CXCL-5, and leptin, was elevated at 8 and at 12 weeks (P < .05). In contrast, expression of CCL3, CCL5, and growth factors (vascular endothelial growth factor, nerve growth factor, epidermal growth factor, granulocyte colony-stimulating factor, and granulocyte macrophage colony-stimulating factor) did not show any significant temporal change after SCI.

CONCLUSION

Spontaneous recovery of reflex voiding at 12 weeks was marked by increased endogenous expression of anti-inflammatory cytokine IL-10 and neuroprotective factors, CXCL-5, and leptin, which suggests that pharmacological suppression of inflammation, can hasten the emergence of reflex voiding after SCI.

Risk factors to develop autonomic dysreflexia during urodynamic examinations in patients with spinal cord injury

AIMS

The risk factors for developing autonomic dysreflexia (AD) during urodynamic (UD) examination in patients with spinal cord injury (SCI) above Th6 still remain unclear. The main goal of our study is to investigate the risk factors that could be associated with AD in these particular patients.

DESIGN

Cross sectional survey.

SUBJECT AND METHODS

The study was carried out in 83 patients with SCI above Th6 who were submitted to our center for a UD examination. AD was defined as a rise in systolic blood pressure above 15 mm Hg with a pulse rate below 60 beats per minute.

RESULTS

The prevalence rate of AD among our patients was 54%. Univariate analysis of our study showed the following risk factors: patient's age, SCI completeness, traumatic etiology, indwelling catheter, presence of chills or sweating, anticholinergic treatment, maximum detrusor voiding pressure, detrusor pressure at maximum flow rate, detrusor external sphincter dyssynergia, and bladder outlet obstruction. Using multivariate logistic regression, we found that there are only two independent risk factors: patient's age equal to or above 45 years of age (OR = 10.995) and maximum detrusor voiding pressure equal to or above 31 cm H₂ O (OR = 3.879).

CONCLUSIONS

According to our results, the patient's age and maximum detrusor voiding pressure should be considered at the time of performing a UD examination in order to prevent the sudden onset of AD in patients with SCI above Th6. Neurourol. Urodynam. 36:171-175, 2017. © 2015 Wiley Periodicals, Inc.