Diabetic Urethral Pathophysiology and Afferent Therapy

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DESCRIPTION (provided by applicant): Diabetes mellitus (DM) is a severe systemic condition that causes serious damage to the lower urinary tract. Diabetic cystopathy is well established, but little is known of DM effects urethral function. Utilizing techniques developed in our laboratory, we propose to mount a systematic in vivo physiological and pharmacological analysis of urethral function in DM animals. Additionally, we propose the first-ever biomechanical analysis of the normal and DM urethra, utilizing techniques developed for vascular biomechanical studies. Complementary in vitro urethral strip studies will also be performed. Finally, we will explore the use of afferent gene therapy to combat the urethral dysfunction caused by DM. We hypothesize: 1) DM results in a functional outlet obstruction caused by incomplete urethral relaxation; 2) DM changes the biomechanical properties of the urethra, contributing to outlet dysfunction; 3) DM results in a disruption of urethral afferent function, thereby contributing to detrusor hypomotility; and 4) Urethral NGF gene therapy can improve urethral innervation in diabetic animals. The Scientific Objectives of this grant are to: 1. Characterize alterations in the physiological and biomechanical properties of the urethra that occur in diabetes using: a) combined isolated cystometry and anterograde urethral perfusion pressure measurements, b) leak point pressure measurements using the vertical tilt table and intravesical pressure clamp, c) whole urethra biomechanical studies, and d) in vitro urethral strip electrical field stimulation studies. 2. Investigate urethral afferent neuropathy in diabetic cystopathy directly by in vivo physiological techniques and in vitro electrophysiological recording of identified urethral afferent neurons, and indirectly by neuroanatomical techniques: a) the effect of intraurethral delivery of irritants on bladder activity will be assessed, b) the phenotypic properties of identified urethral afferent neurons will be determined using patch clamp techniques, and c) immunofluorescent assessment of urethral afferent innervation. 3. Study the novel and exciting potential of gene therapy in the diabetic urethra using a replication-defective, latency-promoter HSV- 1 vector carrying the NGF gene. By defining the urethral pathology of DM, we can offer the hope of prevention, reversal, and even cure of diabetic urologic dysfunction. This is a high priority in the urologic care of diabetic patients.