Acute lower urinary tract dysfunction (LUTD) following traumatic brain injury (TBI) in rats

Assessing Neurogenic Lower Urinary Tract Dysfunction after Spinal Cord Injury: Animal Models in Preclinical Neuro-Urology Research

Neurogenic bladder dysfunction is a condition that affects both bladder storage and voiding function and remains one of the leading causes of morbidity after spinal cord injury (SCI). The vast majority of individuals with severe SCI develop neurogenic lower urinary tract dysfunction (NLUTD), with symptoms ranging from neurogenic detrusor overactivity, detrusor sphincter dyssynergia, or sphincter underactivity depending on the location and extent of the spinal lesion. Animal models are critical to our fundamental understanding of lower urinary tract function and its dysfunction after SCI, in addition to providing a platform for the assessment of potential therapies. Given the need to develop and evaluate novel assessment tools, as well as therapeutic approaches in animal models of SCI prior to human translation, urodynamics assessment techniques have been implemented to measure NLUTD function in a variety of animals, including rats, mice, cats, dogs and pigs. In this narrative review, we summarize the literature on the use of animal models for cystometry testing in the assessment of SCI-related NLUTD. We also discuss the advantages and disadvantages of various animal models, and opportunities for future research.

Best practices for cystometric evaluation of lower urinary tract function in muriform rodents

AIMS

Rodent cystometry has provided valuable insights into the impact of the disease, injury, and aging on the cellular and molecular pathways, neurologic processes, and biomechanics of lower urinary tract function. The purpose of this white paper is to highlight the benefits and shortcomings of different experimental methods and strategies and to provide guidance on the proper interpretation of results.

METHODS

Literature search, selection of articles, and conclusions based on discussions among a panel of workers in the field.

RESULTS

A range of cystometric tests and techniques used to explore biological phenomena relevant to the lower urinary tract are described, the advantages and disadvantages of various experimental conditions are discussed, and guidance on the practical aspects of experimental execution and proper interpretation of results are provided.

CONCLUSIONS

Cystometric evaluation of rodents comprises an extensive collection of functional tests that can be performed under a variety of experimental conditions. Decisions regarding which approaches to choose should be determined by the specific questions to be addressed and implementation of the test should follow standardized procedures.

Urinary dysfunction in acute brain injury: A narrative review

The frontal lobe urinary control center is an important regulator of urinary function. Neurologic injury often causes damage or temporary dysfunction of this center and other related urinary control pathways. Little has been reported about this topic in the literature although a majority of neurologic injury patients suffer from some type of urinary dysfunction. In this review, we highlight what is known about urinary dysfunction based on injury type (traumatic brain injury, hemorrhagic stroke, ischemic stroke, subarachnoid hemorrhage, subdural hematoma, and epilepsy). We discuss both clinical and pre-clinical data and pinpoint areas warranting further investigation. In the final section, we provide proposed practice suggestions for managing these patients clinically with the intended goal for refinement in these approaches following further clinical trials.

Cystometric Measurements in Rats with an Experimentally Induced Traumatic Brain Injury and Voiding Dysfunction: A Time-Course Study

Traumatic brain injuries (TBIs) are a serious public health issue worldwide with increased mortality as well as severe disabilities and injuries caused by falls and road accidents. Unfortunately, there is no approved therapy for TBIs, and bladder dysfunction is a striking symptom. Accordingly, we attempted to analyze bladder dysfunction and voiding efficiency in rats with a TBI at different time-course intervals. Time-dependent analyses were scheduled from the next day until four weeks after a TBI. Experimental animals were grouped and analyzed under the above conditions. Cystometric measurements were used for this analysis and were further elaborated as external urethral sphincter electromyographic (EUS-EMG) activity and cystometrogram (CMG) measurements. Moreover, magnetic resonance imaging (MRI) studies were conducted to investigate secondary injury progression in TBI rats, and results were compared to normal control (NC) rats. Results of EUS-EMG revealed that the burst period, active period, and silent period in TBI rats were drastically reduced compared to NC rats, but they increased later and reached a stagnant phase. Likewise, in CMG measurements, bladder function, the voided volume, and voiding efficiency decreased immediately after the TBI, and other parameters like the volume threshold, inter-contraction interval, and residual volume drastically increased. Later, those levels changed, and all observed results were compared to NC rats. MRI results revealed the prevalence of cerebral edema and the progression of secondary injury. All of the above-stated results of the experiments were extensively substantiated. Thus, these innovative findings of our study model will surely pave the way for new therapeutic interventions for TBI treatment and prominently highlight their applications in the field of neuroscience in the future.

Traumatic Brain Injury-related voiding dysfunction in mice is caused by damage to rostral pathways, altering inputs to the reflex pathways

Brain degeneration, including that caused by traumatic brain injury (TBI) often leads to severe bladder dysfunction, including incontinence and lower urinary tract symptoms; with the causes remaining unknown. Male C57BL/6J mice underwent repetitive moderate brain injury (rmdTBI) or sham injury, then mice received either cis P-tau monoclonal antibody (cis mAb), which prevents brain degeneration in TBI mice, or control (IgG). Void spot assays revealed age-dependent incontinence in IgG controls 8 months after injury, while cis mAb treated or sham mice showed no dysfunction. No obvious bladder pathology occurred in any group. Urodynamic cystometry in conscious mice revealed overactive bladder, reduced maximal voiding pressures and incontinence in IgG control, but not sham or cis mAb treated mice. Hyperphosphorylated tau deposition and neural tangle-like pathology occurred in cortical and hippocampal regions only of IgG control mice accompanied with post-traumatic neuroinflammation and was not seen in midbrain and hindbrain regions associated with bladder filling and voiding reflex arcs. In this model of brain degeneration bladder dysfunction results from rostral, and not hindbrain damage, indicating that rostral brain inputs are required for normal bladder functioning. Detailed analysis of the functioning of neural circuits controlling bladder function in TBI should lead to insights into how brain degeneration leads to bladder dysfunction, as well as novel strategies to treat these disorders.

Improved voiding function by deep brain stimulation in traumatic brain-injured animals with bladder dysfunctions

OBJECTIVE

Traumatic brain injury (TBI) is a global scenario with high mortality and disability, which does not have an effectual and approved therapy till now. Bladder dysfunction is a major symptom after TBI, and this study deals with the alleviation of bladder function in TBI rats, with the aid of deep brain stimulations (DBS).

METHODS

TBI was induced by weight drop model (WDM) and standardized with the experimental subjects with variable heights for weight dropping. The rats survived after TBI were considered for bladder dysfunction observations. DBS with variable stimulation parameters like cystometric analysis and MRI studies were also performed.

RESULTS

After experimental studies, TBI 2-m-height crash was determined as suitable parameter due to minimal mortality rate and significant reduction in the voiding efficiency from 67 to 28%, whereas DBS significantly reversed the value of voiding efficiency to 65-84%. MRI studies revealed the severity of TBI impact and DBS localization.

CONCLUSION

The results showed profound therapeutic effect of PnO-DBS on voiding functions and bladder control on TBI rats.

Bladder telemetry: A new approach to evaluate micturition behavior under physiological and inflammatory conditions

AIMS

To establish a new approach to cystometry using telemetry in conscious rats and to use this technique to determine the role of conscious decision making processes with respect to the initiation of voiding in physiological, inflammatory, and painful conditions.

METHODS

The pressure transducer of a telemetric transmitter was implanted in the dome of the urinary bladder. After a recovery period of at least 1 month, several investigations of urodynamic parameters were performed after diuresis activation by a pulse of furosemide. The model was characterized by tolterodine and mirabegron under physiological conditions and same animals were reused to evaluate the modification of the voiding pattern under bladder inflammation induced by cyclophosphamide.

RESULTS

The quality of traces and measurement of parameters recorded telemetrically were comparable to those with conventional cystometry. Furosemide induced a reproducible transient increase of urine production and a series of voids that persisted for 60 min. Tolterodine reduced the amplitude of micturition contractions although mirabegron was devoid of any effect. Seven hours after injection of CYP, voiding frequency increased significantly and the micturition amplitude contraction was not altered. However, the mean volume voided during individual micturitions and the total voided volume decreased. During a second exposure to furosemide 24H after CYP injection, the micturition pattern returned to control, however, the micturition volume was still lower than in control.

CONCLUSION

This telemetric model appears to be as accurate as previously described in conscious conventional cystometry, and allows the repeated evaluation of compounds which may modulate the voiding patterns. Neurourol. Urodynam. 36:308-315, 2017. © 2016 The Authors. Neurourology and Urodynamics published by Wiley Periodicals, Inc.

Neurogenic Causes of Detrusor Underactivity

Detrusor underactivity (DU) is a poorly understood dysfunction of the lower urinary tract which arises from multiple etiologies. Symptoms of DU are non-specific, and a pressure-flow urodynamic study is necessary to differentiate DU from other conditions such as overactive bladder (OAB) or bladder outlet obstruction (BOO). The prevalence of DU ranges from 10-48%, and DU is most prevalent in elderly males. The pathophysiology underlying DU can be from both neurogenic and non-neurogenic causes. In this article, we review the neurogenic causes of detrusor underactivity, including diabetic bladder dysfunction, spinal cord injury, multiple sclerosis, Parkinson's disease, cerebrovascular accident, traumatic brain injury, and Fowler's syndrome. As knowledge about the underlying causes of DU advances, there have been several potential therapeutic approaches proposed to help those who suffer from this condition.