The overall goal of this procedure is to use transurethral catheter insertion for the intravesical delivery of active substances into the urinary bladder and/or prostate of adult male mice. This method can help answer key questions in the field of bladder pathology about how to study the underlying mechanisms involved in lower urinary tract disease in males. The main advantages of this technique are that it can be used to induce animal models of bladder pathology and to evaluate the effectiveness of intravesicular treatment.

Transurethra instillation in male is challenging due to the natural curvature of the urethra, the thinness of the urethral wall, and the need for repetitive active substance instillation. Before beginning the procedure, select the PE tubing size based on the target organ and the age of the animal, and cut an approximately 2.5-inch long piece from the tube. Dull the sharp edge of a compatibly sized needle on a commercially available oil stone, and carefully introduce the needle into the lumen of one end of the tubing.

Then, immerse the needle and tubing in 70%ethanol, flushing both pieces with ethanol to confirm the absence of leakage. Next, using gentle pressure, massage the lower abdomen of the mouse to induce voiding of the bladder. Then, place the anesthetized animal on a warm heating blanket.

After placing the nose cone, confirm a lack of response to toe pinch, and retract the prepuce. Using the thumb and index finger of one hand, apply pressure to the pubic region and pull out the glans penis with the thumb and index finger of the other hand. Remove the tubing and catheter from the ethanol.

Rinse the tubing and needle in sterile saline and load the needle onto a 1-mL syringe containing the inoculum of interest. Lubricate the tip of the catheter and the glans with sterile surgical lubricant. Gently grasp the tip of the penis with dull forceps and apply gentle pressure to the glans to open the urethral meatus.

Using a tripod finger grip, carefully insert the PE tubing into the meatus, adjusting the angle of the needle to follow the curvature of the urethra as necessary. When the tubing has reached the appropriate organ, depress the plunger to instill the full experimental volume of the inoculum. In these representative images, PE-52 tubing was used to facilitate the transurethral instillation of a blue dye into the mouse urinary bladder, and PE-10 tubing was used to colorize the seminal vesicles and the anterior prostate of a second animal.

However, histological evaluation of the ureters or kidneys is highly recommended to confirm the absence of indirect contamination of the ureters or kidneys from transurethral instillations. Once mastered, this technique can be performed within 10 to 15 minutes if it is performed properly. After watching this video, you should have a good understanding of how to perform transurethra catheterization in an adult male mouse.