Morphometric Analysis of the Collagen Changes Induced by Subcutaneous Injection of Interferon-gamma following Bladder Outlet Obstruction in the Rat

Jung, Jung Yun; Lee, Kyu Sung; Kim, Kwang Myung

Abstract

PURPOSE: Recent studies of bladder outlet obstruction have provided evidence that poor bladder compliance is closely related to collagen content in the bladder wall. To decrease collagen content in the obstructed bladder, we examined the collagen changes by interferon gamma after creating partial bladder outlet obstruction in the rat. Experimental studies of interferon-gamma(IFN-gamma)have been tried to decrease fibrosis in liver disease. We applied interferon-gamma to the obstructed bladder and observed its effect on collagen changes in the bladder wall by morphometric analysis.
MATERIALS AND METHODS
In a total of 50 Sprague-Dawley adult female rats(200- 220gm), we created partial bladder outlet obstruction by placing metal rod (diameter 1 mm). We divided the rats Into 5 groups(n=10 in each group): normal control(N), sham operation(5), sham operation and IFN-gamma4 weeks(S+IFN), bladder outlet obstruction 4 weeks(BOO), and bladder outlet obstruction and IFN-gamma4 weeks(BOO+IFN) groups. IFN- gamma(LG Chemical, Korea) was injected daily(100,000IU) for 4 weeks through subcutaneous route from obstruction day 1 in the injection groups. The rats in each group were sacrificed at 4 weeks of the experimental day and bladder body was prepared for Masson's trichrome special staining. With the image analyser, we calculated the percent collagen area(collagen/collagen muscle) in each bladder.
RESULTS
With obstruction, bladder weights of BOO group and BOO+IFN group were increased 4.6 and 4.4 times, respectively, compared to S group. The percent collagen area in each group was 40.7 1.6% in N group, 38.2 +/-2.0% in S group, 26.6 +/-3.8% in S+IFN group, 19.9 +/-2.5% in BOO group, and 12.4 +/-2.0% in BOO+IFN group(mean+/-standard error). There was no significant statistical difference between N group and S group(p>0.05 by Wilcoxon's rank sum test). On the contrary, there were significant statistical differences between N group and S+IFN group and between S group and S+IFN group. Also there was significant statistical difference between BOO group and BO0+1FN group(p<0.05).
CONCLUSIONS
From the above results, IFN-gamma seems to have the effect to decrease collagen content in the obstructed rat bladder. However, furthers investigations are required to evaluate the therapeutic relevance of IFN-gamma on bladder outlet obstruction patients.