TGF-β1 Effects on Total Collagen of the New Zealand Rabbit's Urethral Wall (Oryctolagus cuniculus) in Animal Models of Urethral Stricture.

Background: Currently, animal models of urethral stricture are not standardized. Transforming Growth Factor Beta 1 (TGF-β1) regulates extracellular matrix deposition in homeostatic and pathological responses.

Objective: The aim of this study was to present the potential model to be developed as a urethral stricture.

Methods: True experimental laboratory research was conducted by using Male New Zealand rabbits (Oryctolagus cuniculus), which were divided into 5 groups; control, placebo, and 3 treatment groups (TGF-β1 injection of 1 µg, 2 µg, 4 µg). Urethrography, histopathological analysis, and evaluation of total collagen formation of the urethral wall were performed after 6 weeks.

Results: An increase in the dose of TGF-β1 decreased the mean rabbit's urethral lumen diameter (29.3% in the 2µg group and 34% in the 4µg group) compared to controls. Three rabbits decreased as much as ≤ 50% in urethral lumen diameter. Significant increases in total collagen density in the periluminal and peripheral urethral spongiosum were noted by increasing doses of TGF-β1. The percentage of urethral lumen diameter has a strong negative correlation with periluminal total collagen density (r = -0,798; p = 0,000) and very strong negative correlation with peripheral spongiosa total collagen density (r = -0,748, p = 0,000).

Conclusion: TGF-β1 plays a role in changing total collagen compositions of the rabbit's urethral wall, decreasing the urethral lumen diameter. Further research with increasing doses of TGF-β1 is needed to determine the effective dose of TGF-β1 in inducing urethral stricture.