Dog model for studying detrusor instability secondary to acutely induced variable bladder outlet obstruction

Benefits and limitations of animal models in partial bladder outlet obstruction for translational research

The functions of the lower urinary tract have been investigated for more than a century. Lower urinary tract symptoms, such as incomplete bladder emptying, weak urine stream, daytime urinary frequency, urgency, urge incontinence and nocturia after partial bladder outlet obstruction, is a frequent cause of benign prostatic hyperplasia in aging men. However, the pathophysiological mechanisms have not been fully elucidated. The use of animal models is absolutely imperative for understanding the pathophysiological processes involved in bladder dysfunction. Surgical induction has been used to study lower urinary tract functions of numerous animal species, such as pig, dog, rabbit, guinea pig, rat and mouse, of both sexes. Several morphological and functional modifications under partial bladder outlet obstruction have not only been observed in the bladder, but also in the central nervous system. Understanding the changes of the lower urinary tract functions induced by partial bladder outlet obstruction would also contribute to appropriate drug development for treating these pathophysiological conditions. In the present review, we discuss techniques for creating partial bladder outlet obstruction, the characteristics of several species, as well as issues of each model, and their translational value.

Prostatic elasticity: a new non-invasive parameter to assess bladder outlet obstruction caused by benign prostatic hyperplasia (a canine experiment)

OBJECTIVE

To evaluate the change of prostatic elasticity during the development of benign prostatic hyperplasia (BPH) and its correlation with the degree of bladder outlet obstruction (BOO) in the canine model of BOO caused by BPH.

MATERIALS AND METHODS

Ten male beagle dogs were selected in this study. To establish canine model of BOO caused by BPH, each beagle underwent castration surgery followed by encapsulating the prostate with a double layer of nylon mesh and then treating the beagles with a combination of steroids for 12 weeks. Transrectal ultrasound (TRUS) examination and urodynamic evaluation were performed before and at 4, 8, and 12 weeks of hormone administration. Prostatic volume, Young modulus of prostatic tissue, and urodynamic parameters were compared at each time instance, and the correlation between the Young modulus of the prostatic tissue and urodynamic parameters were evaluated.

RESULTS

All beagles developed BOO caused by BPH over the time period of the study. Prostatic volume, Young modulus of prostatic tissue, and urodynamic parameters had statistically significant differences before and after 4, 8, and 12 weeks of hormone administration (P <.05). Young modulus of prostatic tissue showed a very significant correlation with urodynamic parameters, including maximum urine flow (Qmax) (r = -0.802, P <.01), Qave (r = -0.711, P <.01), Pves@open (r = 0.638, P <.01), Pves@Qmax (r = 0.699, P <.01), Pdet@Qmax (r = 0.757, P <.01), and Pdetmax (r = 0.739, P <.01).

CONCLUSION

Young modulus of prostatic tissue increased during the development of the BPH. There was a significant correlation between Young modulus of prostatic tissue and the degree of BOO.

Clinical aspects of the overactive bladder and detrusor overactivity

OBJECTIVE

The overactive bladder is a widespread medical condition with significant quality of life and financial impact. Despite this much remains unknown about the epidemiology and pathophysiology of this condition. This review gives an overview of the current knowledge base and the recent terminology changes approved by the international continence society.

METHODS

Critical review of the literature regarding aetiology, epidemiology, urodynamic and clinical aspects of detrusor overactivity. Explanation of the recently adopted terminology.

RESULTS

The term "overactive bladder" has replaced the term "unstable bladder", which held no intuitive meaning. "Detrusor overactivity" is the corresponding urodynamic term, replacing "detrusor instability" and "detrusor hyperreflexia". Knowledge regarding the epidemiology of the overactive bladder is limited. The myogenic and neurogenic theories of pathophysiology require further evidence.

CONCLUSION

Massive research efforts are required into all aspects of this common chronic disease. The adoption of new ICS terminology will aid consistency in research.

Overactive detrusor

Detrusor overactivity poses a major challenge to physicians from many specialities. Progress in our understanding of the pathogenesis of detrusor overactivity is slow but steady. Advances in treatment continue to be made, both with new agents and new methods of delivering older drugs. Neuromodulation is showing great promise as experience increases, and developments in bladder augmentation offer hope for lower morbidity treatments in future.