Initial observations of reduced uroflow in transgenic adenocarcinoma of murine prostate.

OBJECTIVES

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.

METHODS

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.

RESULTS

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.

CONCLUSIONS

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.