The Research For Improved Method To Establish The Urethral Stricture Model In Rabbit

Objective: To explore a method for establishing a model that is economical,simple,and reproducible by improving the modeling method of urethral stricture,and lay a foundation for the study of the mechanism of subsequent urethral stricture.Methods: In this study,28 adult male New Zealand rabbits were selected.The random number table method was used to divide them according to the ratio of 1:3:3.Normal control group,4 rabbits,only ureteroscopy urethral examination.In the conventional model group,12 rabbits were treated with ring electrocoagulation for anterior urethra with selfmade electric knife tip,about 5mm long,until urethral mucosa became pale.In the improved model group,12 rabbits were treated with self-made electrocoagulation guidewire under ureteroscopy and the anterior urethral punctiform ring electrocoagulation was about 5mm long and reached to the submucosa.On the 30 th day after modeling,retrograde urethrography and ureteroscopy were performed to evaluate the formation of urethral stricture,and histopathological examination was performed on the tissue of the corresponding surgical site.Meanwhile,the expression changes of TGF-?1,Smad3 and MMP1 in the tissue were detected by immunohistochemistry and real-time quantitative PCR.Results:1.The formation of rabbit urethral stricture model: After retrograde urethrography and urethroscopic examination,4 rabbits in the normal control group were routinely fed without death and urethral stricture.In the conventional model group,3 rabbits were found to form urethral stricture,5 were found to form urethral atresia,3 were complicated with urinary fistula,and 1 died.All the 12 rabbits in the improved model group were found significant urethral stricture and there was no rabbit to die.2.The expression levels of TGF-?1,Smad3 and MMP1 m RNA and protein were higher in the two model groups than in the normal control group(P<0.05).The expression levels of Smad3 and MMP1 m RNA in the conventional model group were significantly higher than those in the improved model group(P<0.05),and there was no significant difference in TGF-?1 m RNA expression between the two model groups(P>0.05).There was no significant difference in the expression of protein levels of TGF-?1,Smad3 and MMP1 between the two model groups(P>0.05).Conclusions:1.1.The expression levels of TGF-?1,Smad3 and MMP1 m RNA and protein in scar tissue of rabbit urethral stricture increased.2.The improved model group can successfully establish a urethral stricture model by point-shaped circular electrocoagulation under ureteroscopy.It has high rate for success,simple method and high reproducibility.It can be used as an effective method to build the urethral stricture model for a male rabbit.There are many complications in the conventional model group,which can form urethral atresia and urinary fistula leading to death in rabbits.It is not a preferable method to establish the urethral stricture model for a rabbit.