Vascular endothelial growth factor expression in the urethral epithelium of castrated adult female rats treated with tamoxifen

Effects of anastrozole on Ki-67 antigen expression in the vaginal epithelium of female rats in persistent estrus

OBJECTIVES

Aromatase inhibitors are the first-choice drugs for the treatment of hormone sensitive breast cancer. However, in addition to the scarcity of studies, there are controversies about their effects on vaginal epithelial cell proliferation in rats, especially those in persistent estrus.

METHODS

To investigate vaginal epithelial cell proliferation by Ki-67 antigen expression, persistent estrus was induced in 42 randomly selected rats. These rats were randomly divided into 2 groups: group I (control, n=21), which received 0.1 mL of propylene glycol (vehicle) daily, and group II (experimental, n=21), which received 0.5 mg/kg or 0.125 mg/day of anastrozole diluted with 0.1 mL of propylene glycol.

RESULTS

Light microscopy showed a higher concentration of cells with brown Ki-67 stained nuclei in the control compared to the experimental group. The mean percentage of Ki-67 stained nuclei per 500 cells in the vaginal epithelium was 68.64±2.64 and 30.46±2.00 [mean±standard error of the mean (SEM)] in the control and experimental groups, respectively (p<0.003).

CONCLUSION

This study showed that anastrozole, at the dose and treatment duration selected, significantly decreased cell proliferation in the vaginal mucosa of the rats in persistent estrus.

Ki-67 antigen expression in the mammary epithelium of female rats in persistent estrus treated with anastrozole

OBJECTIVES

To evaluate Ki-67 antigen expression in mammary epithelium of female rats in persistent estrus treated with anastrozole.

MATERIALS AND METHODS

Twenty-eight Wistar-Hanover female rats in persistent estrus induced by subcutaneous injection of 1.25 mg of testosterone propionate in the second day of life were randomly divided into two groups, control and experimental, with 14 animals each. The animals of control group received only the vehicle (propyleneglycol) and the animals of group experimental received 0.125 mg daily of anastrozole by gavage during 28 days. After 28 days of treatment, all animals were sacrificed and the first pair of abdominal-inguinal mammary glands was removed and fixed in 10% buffered formalin to investigate Ki-67 antigen expression by immunohistochemistry.

RESULTS

The mean percentage of Ki-67-stained nuclei per 500 cells in the mammary epithelium was 76.97 ± 0.76 and 14.44 ± 2.02 [mean ± standard error of the mean (SEM)] in the control and experimental groups, respectively (p < 0.0001).

CONCLUSIONS

Anastrozole treatment significantly reduced Ki-67 expression in the mammary epithelium of rats in persistent estrus.

Analysis of the Ki-67 index in the vaginal epithelium of castrated rats treated with tamoxifen

OBJECTIVES

Vaginal atrophy and breast cancer are common conditions in postmenopausal women and tamoxifen is the standard endocrine treatment for hormone-sensitive tumors. The present study aimed to assess the effect of tamoxifen on Ki-67 protein expression in the vaginal epithelium of castrated rats.

MATERIAL AND METHODS

Forty Wistar-Hannover adult, virgin, castrated rats were randomly divided into two groups, group I (control, n=20) and group II (tamoxifen, n=20), receiving 0.5 ml of propylene glycol and 250 µg of tamoxifen diluted in 0.5 ml of propylene glycol, respectively, daily by gavage for 30 days. On the 31st day, the rats were euthanized and their vaginas were removed and fixed in 10% buffered formalin for the immunohistochemical study of Ki-67 protein expression. Data were analyzed by the Levene and Student's t tests (p<0.05).

RESULTS

The mean index of Ki-67 expression in the rat vagina of groups I and II was 4.04±0.96 and 26.86±2.19, respectively (p<0.001).

CONCLUSIONS

According to the results of the present study, tamoxifen, at the dose and treatment length used, induced a significant increase in the cell proliferation of the vaginal mucosa in castrated rats, as evaluated by Ki-67 protein expression.

Effect of tamoxifen on extracellular signal-regulated kinases in the urethra of castrated female rats

OBJECTIVE

The aim was to evaluate the effects of tamoxifen in activating extracellular signal-regulated kinases (ERKs) 1 and 2 in the urethras of castrated female rats.

STUDY DESIGN

Twelve castrated adult female rats were divided into a control group (n=6) in which the animals received vehicle, and the experimental group (n=6) in which the rats received tamoxifen 250 μg/day by gavage for 28 days. Then, the animals were sacrificed and their urethras removed. Proteins were extracted, quantified and processed by Western blot analysis with specific phospho-ERK1 and 2 antibodies. Data were analyzed using Student's t-test (p<0.05).

RESULTS

A significant increase occurred in phospho-ERK1 levels in the experimental group compared to the control group (p<0.01), while no difference was found in phospho-ERK2 levels between the groups (p=0.313).

CONCLUSION

The present results indicate that, at the doses and during the time of treatment used, tamoxifen significantly increased phospho-ERK1 levels in the urethras of castrated female rats.