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

Abstract

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 μg of raloxifene or 250 μg 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.

Chinese abstract

目的：该研究的目的是评估雷洛昔芬和它莫昔芬治疗对去势雌鼠阴道上皮细胞Ki-67 抗原表达的影响。

实验方法：将39只未性交鼠、成年以及去势的雌性Wistar–Hannover鼠随机分为三组：第一组（对照组，n=13），第二组（雷洛昔芬治疗，n=13），第三组（它莫昔芬治疗，n=13）。确认处于低雌激素状态后，分别连续30天分别给0.5ml的丙二醇（媒介），750μg的雷洛昔芬和250μg的它莫昔芬灌胃。在第31天，对鼠进行安乐死处死，取下其阴道，固定在10%的福尔马林缓冲液中，进行Ki-67免疫组织化学评估,用Levene’s test and Tukey’s的方法处理数据(p<0.05)。

实验结果：I，II，III组的Ki-67表达的平均值为分别为27 ± 2.6, 32.3 ± 1.9 and 43.7 ± 3.5。相比于第一组和第二组，第三组（它莫昔芬处理）中的染色细胞比例更大（p<0.0003），而第一组和第二组在数据统计上没有明显差异（p=0.3626）。

实验结论：目前的研究结果表明，它莫昔芬对去势大鼠阴道上皮细胞的增殖具有显著的增强作用，而雷洛昔芬治疗组和对照组之间无明显差别。

• Castrated female rat
• postmenopause
• raloxifene
• SERMs
• tamoxifen

Acknowledgements

The authors thank to Health and Sciences Postgraduate Program of Federal University of Piauí for its contribution in the qualification of human resources in northeastern Brazil.

Declaration of interest

The authors declare that they have no competing interests.