Initial observations of reduced uroflow in transgenic adenocarcinoma of murine prostate

To characterize the voiding function in a transgenic adenocarcinoma of murine prostate (TRAMP) mouse of advanced age, because it might provide a useful model of slow-onset bladder outlet obstruction. Spontaneous death from urinary outlet obstruction occurs in the TRAMP mouse.

A metabolic cage without a fecal separation screen was placed above a precision balance that reported the mass of the excreta pan every 100 ms. A computational algorithm identified voids suitable for uroflow assessment from other excretory events. A series of images were obtained automatically before and during the excretory events.

The TRAMP mouse displayed a pulsatile voiding pattern characterized by a reduction in uroflow, prolongation of voiding, and droplet formation at the tip of the prepuce. Postmortem histologic examination revealed gross enlargement of the prostate, a suburethral tumor, dilation of the lumen of the urethra, and proteinaceous debris in the urethra and bladder.

The observed changes were consistent with urethral obstruction induced by prostate enlargement and/or suburethral tumor. Additional studies are required to ascertain whether prostate enlargement per se is sufficient to produce urethral obstruction in the TRAMP mouse. This transgenic mouse strain may provide a model of slow-onset outlet obstruction that is more representative of bladder outlet obstruction caused by benign prostatic hyperplasia than is the obstruction produced by urethral ligation.