Evaluation of Ki-67 antigen expression in the vaginal epithelium of castrated female rats treated with raloxifene and tamoxifen: a comparative study

Objective: The aim of this study was to evaluate the effects of raloxifene and tamoxifen on Ki-67 antigen expression in the vaginal epithelium of castrated rats. Material and methods: Thirty-nine virgin, adult, castrated female Wistar-Hannover rats were randomly divided into three groups: Group I (control, n = 13), Group II (raloxifene, n = 13) and Group III (tamoxifen, n = 13). After confirmation of their hypoestrogenic state, the rats were given 0.5 ml of propylene glycol (vehicle), 750 mu g of raloxifene or 250 mu g of tamoxifen, respectively, by gavage, for 30 days. On the 31st day, the rats were euthanized and their vaginas removed and fixed in 10% buffered formalin for of Ki-67 immunohistochemical evaluation. Data were analyzed using Levene's test and Tukey's method (p<0.05). Results: Mean Ki-67 expression in groups I, II and III was 27 +/- 2.6, 32.3 +/- 1.9 and 43.7 +/- 3.5, respectively. In Group III (tamoxifen), there was a greater proportion of stained cells compared to Groups I and II (p<0.0003), with no statistically significant difference between Groups I and II (p = 0.3626). Conclusions: The present results show that tamoxifen significantly increased cell proliferation in the vaginal epithelium of the castrated rats and no difference between the raloxifene and control groups.