SIDE-EFFECTS OF TAMOXIFEN IN OOPHORECTOMIZED RATS

Objective: Our objective was to evaluate the direct effect of tamoxife n citrate (TAM) on the endometrium, liver, breast tissue and the lipid profile in oophorectomized (OX) rats. Study Design: An experimental a nimal study. Material and Methods: Forty-one mature rats (33 OX) were randomly divided into four groups and received either TAM (0.4 or 0.8 mg/kg p.o.) therapy or placebo over 60 days as follows: (1) sham; (2) OX + TAM (0.4 mg/kg); (3) OX + TAM (0.8 mg/kg); (4) OX. All histologic al changes in the endometrium, liver and breast tissue were evaluated under the light microscope by comparing the TAM-treated groups with th e OX and sham-operated groups. Blood total cholesterol and low-density lipoprotein cholesterol levels were also analyzed. Results: TAM-treat ed rats showed a significant reduction in body weight, blood cholester ol and low-density lipoprotein cholesterol levels, but the wet uterine weight was not affected. Estrogenic effects of TAM were not detected with either dosage on the endometrium. TAM-treated groups showed atrop hic breast tissue. No histopathological changes were detected in the l iver with TAM treatment. Conclusion: The data suggests that TAM may no t act as an estrogen receptor agonist with the given dosage on the end ometrium in OX rats. Two different doses of TAM do not cause histologi cal changes in liver over 60 days of treatment.