Morphometric analysis of the collagen changes induced by subcutaneous injection of interferon‐gamma after bladder outlet obstruction in the rat

Aims: The objective of this study was to examine the effects of interferon‐gamma injection on changes in collagen content, after the creation of partial bladder outlet obstruction in the rats. Methods: A total of 50 Sprague‐Dawley female rats were subjected to partial bladder outlet obstruction by using metal rods. The rats were divided into five groups (n = 10 in each group): normal control (N), sham operation (S), bladder outlet obstruction for 4 weeks (BOO), interferon‐gamma injection after sham operation (S + IFN), and interferon‐gamma injection after bladder outlet obstruction (BOO + IFN). Interferon‐gamma was subcutaneously injected (100,000 units per injection, LG chemical Co., Seoul, Korea) daily for 4 weeks in the injection groups, after which all rats were sacrificed. Results: The collagen area percentage (collagen/collagen + muscle) in each bladder, calculated through image analysis, was 40.7 ± 1.6% in the N, 38.2 ± 2.0% in the S, 26.6 ± 3.8% in the S + IFN, 19.9 ± 2.5% in the BOO, and 12.4 ± 2.0% in the BOO + IFN group (mean ± standard error). The difference in the collagen area percentage between the N and S groups ( P  > 0.05) was not significant, but there were significant differences between the N and S + IFN groups ( P  < 0.05), between the S and S + IFN groups ( P  < 0.05), and between the BOO and BOO + IFN groups ( P  < 0.05). Conclusions: It appears that interferon‐gamma decreases the collagen content in the obstructed rat bladder. Neurourol. Urodynam. 22:70–76, 2003. © 2003 Wiley‐Liss, Inc.