RESUMO
OBJECTIVE: To investigate the preventive effect of local injection of botulinum toxin type A (BTX-A) against iatrogenic anterior urethral stricture (IAUS) in New Zealand male rabbits. METHODS: Sixteen adult New Zealand male rabbits were randomly divided into an experimental and a control group of equal number. The model of IAUS was established in the rabbits by incision of the ventral urethra of the penile segment and electrocoagulation of the urethral mucosa. The rabbits of the experimental group were injected with 10 U of BTX-A solution and those of the control group with 1.0 ml of normal saline into the electrocoagulated submucosa of the urethra. At 30 days after modeling, retrograde urethrography was performed and the scarred urethral tissue harvested for HE and Masson staining. RESULTS: No systemic symptoms of botulinum toxin poisoning were observed in either group of the rabbits. Retrograde urethrography showed statistically significant differences between the control and experimental groups in the diameter of the urethra (ï¼»0.15 ± 0.08ï¼½ vs ï¼»0.50 ± 0.23ï¼½ cm, P < 0.05) and the stenosis ratio (3.68 ± 1.22 vs 1.29 ± 0.15, P < 0.05). Urethrography revealed obvious hyperplasia and contracture of urethral scar with high bulge and narrow urethral cavity, while HE and Masson staining exhibited absence or discontinuity of the urethral epithelium, submucosal fibrosis with infiltration of a large number of fibroblasts, and hyperplasia and thickening of collagen fibers (blue) in the control group. All the changes above were slight and the urethral epithelium was continuous in the experimental group. CONCLUSIONS: Local injection of BTX-A reduced the incidence of iatrogenic anterior urethral stricture after iatrogenic acute heat injury in New Zealand male rabbits.